This makes perfect sense.All but the emergencies. I have small blennies in all my tanks and they sometime like to go overflow surfing lol. I turnover a ton of water, so if they go down a pipe, it is usually not good for them. Much easier to turn off pump, lift drain pipe up with gate valve all the way open and catch in a net. If they just went down, they would be beat up and then land in a group of non-photsynthetic nems in the sumps lol.
When I restocked the 120 I put a black Molly in the tank. It either got eaten by a tube, or down the overflow. I would not be at all surprised to find it still alive in the sump when I tear everything down.