Great question, I have no idea what the answer should be.
But I have found less is best. I think that's the main reason why people find a bunch of dead snail a few weeks or months after getting them. They fail to feed them after all the algae is depleted.
I have a lawn mower blenny that I haven't directly feed in 8 months. Because I have indirect light causing algae and a sparse clean up crew. I have a conch that I feed a sinking pellet once a week. Just picked up two emerald crabs they are good for bubble algae and some other nucience stuff but they need meaty food when they get bigger or they will eat your snails.
Any hermit crab I've ever had ate snail, even when I provided many empty shells.
Large turbos knock a suprising amount of stuff over. Need sand bed for Nassarius snails
In short get a few to start and then add if required