You set a clean RM150 daily budget across three ad sets, hit publish, and check back the next morning. One ad set has swallowed almost the whole budget. The other two spent a few Ringgit between them. Nothing looks broken — yet your spend is nowhere near even.
This is one of the most common questions Malaysian advertisers ask about Meta’s campaign budget optimisation — usually shortened to CBO, and now branded Advantage campaign budget. People assume a shared budget means a shared split. It rarely works that way. Across the Meta Ads campaigns we manage for 500+ Malaysian businesses, a CBO budget not distributing the way an owner expected is something we explain almost every week.
This guide covers why CBO skews spend toward one ad set, when that is a problem and when it is not, the exact steps to fix it, and how to stop it catching you out again. The short video below breaks down how CBO decides where your money goes.
Source video: What is Facebook CBO? How Does Facebook Campaign Budget Optimization Work? (Full Guide) on YouTube
Quick Answer: Your CBO budget is not distributing evenly because it was never meant to. Campaign budget optimisation — Meta’s Advantage campaign budget — hands more money to whichever ad set it predicts will get the cheapest result. A lopsided spread is the default behaviour, not a fault.
With CBO, you set one budget at the campaign level and Meta decides how to share it across your ad sets in real time. Every few minutes it re-reads which ad set is winning cheaper results and shifts spend toward it. The goal is the most results for your Ringgit — not a tidy even split.
Set budgets at the ad set level instead (the old default, now called ABO) and each ad set gets exactly what you give it. Turn CBO on and you hand that decision to the algorithm. So the very feature you switched on is what pushes your spend onto one or two ad sets. It leans hardest during the early days, when a campaign is still in its learning phase and testing where results come cheapest.
Quick Answer: Often it is not. If the ad set eating the budget is also bringing the cheapest leads or sales, CBO is doing exactly what you want. It turns into a real problem only when the favoured ad set has a tiny audience, a different goal, or the results behind the spend do not hold up.
Before you fix anything, check whether there is anything to fix. The first move is to look past the spend column and read the result column. Uneven spend with strong, cheap results is a win, not a bug — this is different from your ads not delivering or spending at all, which is a genuine delivery fault.
Uneven distribution deserves a closer look when you spot these signs:
Diagnosing this is a bit like tracing a sudden drop in your search rankings — read the data first, then decide whether to act. Jumping in to force an even split can undo the efficiency CBO was giving you.
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Quick Answer: Most lopsided CBO campaigns trace back to ad sets that are not comparable — very different audiences, very different sizes, or mixed goals — plus spend limits and the learning phase. When Meta cannot judge your ad sets fairly, it simply backs one and starves the rest.
When we audit a campaign where the CBO budget is not distributing well, the cause is rarely mysterious. It is almost always one of five setup issues — and knowing which one points you straight at the fix.
| Cause | What goes wrong | Share of flagged campaigns |
|---|---|---|
| Ad sets target very different audiences | Algorithm backs the one it predicts is cheapest and starves the rest | 34% |
| One audience far larger than the others | The big audience soaks up the spend, niche ones never scale | 23% |
| Ad set spend limits fighting the algorithm | Min or max caps force money where it would not naturally flow | 16% |
| Still in the learning phase | Early exploration looks lopsided before spend settles | 15% |
| Mixed objectives or optimisation events | Meta cannot compare ad sets fairly, so it picks one | 12% |
Source: ZenWeb client onboarding audits, 500+ Malaysian SME accounts, 2024–2026.
Spend limits deserve a special mention. Owners often add them to force a fairer split, then find delivery stalls instead — a close cousin of hitting a Facebook ad spending limit that quietly caps the account.
Quick Answer: Bad CBO distribution rarely fails loudly — it leaks money quietly. Starved test ad sets never reach a verdict, your one winner saturates and its costs creep up, and cheaper backup audiences never get the spend to scale. On a RM10,000 budget, that hidden drag can run into the thousands.
When the split is genuinely wrong, the damage hides in plain sight. Nothing errors out — the campaign just quietly earns less than it should. Much like a wrong-currency ad account that bleeds you slowly, the cost only shows up when you add it all up.
| Hidden cost | Est. monthly drag | Relative size |
|---|---|---|
| Starved test ad sets never exit learning | ~RM1,500 | |
| Winning audience saturates, frequency climbs | ~RM1,200 | |
| Cheaper backup audiences never scale | ~RM900 | |
| Manual budget babysitting time | ~RM600 |
Illustrative scenario modeled on a RM10,000/month budget. Actual figures vary by account and objective.
Lopsided spend rarely breaks a campaign outright — it just quietly siphons a chunk of every Ringgit into tests that never finish and audiences that never scale.
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Quick Answer: To fix uneven CBO spend, first confirm it is actually hurting results, then make your ad sets comparable, add gentle ad set spend limits, wait out the learning phase, and move fresh tests into a separate ABO campaign. Change one thing at a time so you can see what worked.
These steps take a lopsided CBO campaign back to a fair, results-led split without throwing away the efficiency the algorithm gives you. Work through them in order.
Follow these seven steps to get spend flowing to the ad sets that deserve it.
If a fair split still will not hold after all this, the structure itself may need a rebuild — something our Meta Ads team handles day in, day out.
Quick Answer: CBO hands budget control to Meta and chases the cheapest result across your ad sets. ABO keeps control with you and spends exactly what you set per ad set. Use CBO to scale proven audiences, and ABO when you need guaranteed, even spend for testing.
If you need spend to land evenly, the honest fix is often not to wrestle CBO — it is to use the right budget type for the job. Here is how the two compare.
| Factor | CBO (Advantage campaign budget) | ABO (ad set budget) |
|---|---|---|
| Who controls spend | Meta spreads it across ad sets | You set a fixed budget per ad set |
| Distribution | Lopsided by design, chases cheapest result | Exactly even — you decide the split |
| Best for | Scaling audiences that already work | Testing new audiences and creatives |
| Learning phase | Shared across ad sets, faster to exit at volume | Per ad set, slower on small budgets |
| Pick it when | Winners are clear and you want scale | You need guaranteed spend on every audience |
Source: ZenWeb campaign management playbook, Malaysia, 2024–2026.
Neither is better in the abstract — they answer different questions. A common winning setup is ABO to find the audiences that work, then CBO to pour budget into them. Our managed Meta Ads campaigns switch between the two as each campaign matures.
Quick Answer: The share of CBO campaigns flagged for lopsided spend is climbing, not falling. As Meta makes Advantage campaign budget the default and pushes more automation into every campaign, more Malaysian advertisers hit uneven distribution without ever choosing to turn CBO on.
You might expect this to fade as advertisers get more experienced. The opposite is happening. Meta keeps making campaign-level budgeting the default path, so more owners run CBO without realising it — and meet uneven spend by surprise.
| Quarter | Share flagged | Trend |
|---|---|---|
| Q1 2024 | 28% | |
| Q3 2024 | 33% | |
| Q1 2025 | 38% | |
| Q3 2025 | 42% | |
| Q1 2026 | 45% |
Source: ZenWeb onboarding data, Malaysian SME CBO campaigns, 2024–2026.
As automation takes over more of the account — budgets, placements, audiences — the same shift shows up elsewhere, from delivery quirks to more ads getting rejected by automated review. Understanding how the automation thinks is now part of the job.
Quick Answer: Prevention is a structure habit: group only comparable audiences in a CBO campaign, keep new tests in ABO, and read results at the campaign level. Build campaigns this way from the start and lopsided spend rarely surprises you again.
Once you have untangled one lopsided campaign, you will not want to repeat it. These habits keep distribution healthy from day one:
A CBO budget not distributing evenly feels like a fault, but most of the time it is the algorithm backing its predicted winner — exactly what campaign budget optimisation is built to do. The job is not to force an even split; it is to make sure CBO is backing the right ad set, then get out of its way.
Make your ad sets comparable, keep testing in ABO, use spend limits with a light touch, and judge results at the campaign level. If the split still will not behave, the structure likely needs a rebuild. The team at ZenWeb restructures Meta campaigns for Malaysian businesses every day, so if you would rather hand it over, our Meta Ads management gets your spend following results instead of guesswork.
Because CBO — Advantage campaign budget — is built to chase the cheapest result, not an even split. It reads which ad set is winning results most cheaply and shifts spend toward it in real time. If that ad set is also your best performer, this is CBO working as intended, not a bug to fix.
Not exactly evenly, but you can guide it. Ad set spend limits let you set a minimum (and maximum) per ad set, so every audience gets a floor of spend for a fair test. Use them lightly — stacking hard caps fights the algorithm and can stall delivery. For truly even spend, ABO is the better tool.
It depends on the job. CBO is better for scaling audiences that already convert, because it pushes budget to winners automatically. ABO is better for testing, because it guarantees each audience the spend you set. Many Malaysian advertisers test in ABO, then move proven audiences into CBO to scale.
Yes. During the learning phase, CBO explores and spend looks lopsided while Meta gathers data. It often settles once the campaign exits learning. Judging distribution too early, or making changes that restart learning, keeps a campaign looking uneven for longer than it needs to.
Use them sparingly. A gentle minimum spend can protect a test audience you care about, but every cap you add reduces the efficiency CBO is meant to give you. If you find yourself capping most ad sets, that is a sign the campaign should be running on ABO instead.
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