Take a skincare shop doing about 40 orders a month on a fresh Meta account. The old playbook was three or four interest stacks, narrow audiences, and hope the pixel data trained the system. Now plenty of people just switch on Advantage+ audience with only age and location set and let Meta find the buyers.
Honestly, I think interest stacks mattered most when the algorithm had plenty of conversion data to learn from. At thin volume they're mostly a guess about who buys. Going broad only works if the creative does the targeting, because the hook has to make the right person stop scrolling.
I'd still start broad for 2 to 3 weeks, but only once the purchase event is firing cleanly. What are you seeing at low volume?