What you control and what you hand over
You control the product, the target ROI, the daily budget and the pool of videos TikTok can pull from. You do not control audiences, placements or which video runs. The system reads your organic and creator content and promotes whatever converts.
That makes content supply the main lever. Accounts with three videos starve the system. Accounts feeding 20 to 40 videos a month, including creator content authorised through Spark, give it room to find winners.
Setting the ROI target
Start the target at or slightly below your current blended ROAS on TikTok Shop, then raise it in small steps. Set it too high and delivery caps, so the campaign spends a fraction of budget. Set it too low and you buy unprofitable GMV fast.
Change the target no more than once every 3 to 4 days and move it by 10% to 15% at a time. Every change restarts learning. Judge the campaign on a rolling 7-day window, because daily swings on Shop ads are severe.
When it works and when it does not
It works for catalogues with proven sellers, decent review counts and reliable stock. It struggles on new products with no sales history, because there is no signal to optimise against and budget parks itself on your existing bestseller.
Launching something new needs separate support. Use creator seeding, Spark Ads on the strongest organic videos and live sessions to build first sales, then hand the product to GMV Max once it has traction.