If your product categories have different customer intents, creatives, or margins, then yes, separate PMax campaigns are better.
If they're similar or part of a tight niche, one campaign with multiple asset groups can work just fine.
When to create separate PMax campaigns:
Different product categories or verticals
(e.g., running shoes vs. yoga mats vs. supplements)
→ Each category may have distinct audiences, creatives, and performance metrics.
You want more control over budgets
Separate campaigns = separate budgets. If you're spending heavily, this helps avoid starving important categories.
You need cleaner reporting or ROAS optimization per category
Google doesn't let you set ROAS per asset group — only per campaign. So splitting by campaign lets you optimize per category.
You have different seasonality or promo periods per category
When one campaign with multiple asset groups works:
All products serve the same audience type
You have low spend or limited conversion volume
(Google needs 50+ conversions/month to optimize well — splitting too much can hurt learning)
Your categories have overlapping keywords and visuals
You're in testing or early-growth phase
Pro Tip: Hybrid strategy works best
Start with 1 PMax campaign, use asset groups to separate categories.
Once a category shows consistent traction and scale, spin it out into its own campaign for tighter control.
This gives you:
- Better learning early on
- Easier management
- Flexibility to scale what works