I've done as low as 8 (with 3 rare) for a small gacha. I think on average, a minimum of 10-15 works well

One.

I think when I asked this, the consensus was 8 to 12

Vaki: that's my usual philosophy too! but i made something that so perfectly lends itself to that format so, im gonna give it a go.

i have 7 items....throw a few variations in the mix and i'm good. thanks guys.