Mine are like dogs. they all float up to the top and wait about 5-10 minutes before it spins. The cryptic foxface comes out when the motor whirrs as its dropping the food.They’ll likely survive but you’d be putting them in a compromising position. Hungry fish are more prone to aggression and disease. Why risk it over a cheap device?
I keep my auto feeder on and running pellets every other day, and feed other stuff manually. If I ever forget to feed or head out of town, they still get a consistent feeding. Interesting behavior too as they seem to know what time of day it is before the thing even goes off. Fun to watch.