When you're running a DCT (Dynamic Creative Test) to compare variations of a winning ad, it's generally better to let it run freely without a bid cap—at least in the testing phase.
Bid Cap Can Throttle Delivery
If your bid cap is set too low, Meta may not spend enough to properly test all creative combinations. That means you might miss identifying strong performers.
DCT Needs Flexibility
Meta's algorithm needs room to explore which combos (headline + image + copy) work best. A bid cap limits this learning process.
Testing = Learning Phase
Your main goal here is to gather insights, not drive immediate efficiency. Once you find your top-performing combos, then you can apply bid strategies like Bid Cap or Target CPA to control costs during scaling.
What You Should Do Instead:
- Use lowest cost (no cap) bidding for initial DCT runs.
- Let it run for 3–5 days with a decent budget to give the algorithm enough room.
- Once winners emerge, build a new campaign using only the best creatives—and then test Bid Cap for control.