I do believe that the hatcheries do. But, they have high tech thermostats. In fact, they spend as much time trying to get the temp DOWN in the mega hatchers as they do keeping it up during the early incubation phases. IMO, for the home hatcher, best practice might be to drop a degree before hatch, but in reality, we're left dealing with thermostats and thermometers that lack a high degree of accuracy. So, for most of us, once we get the thermostat zeroed in at an acceptable number, it's a mental challenge to mess with it when we're so close to the finish line. When I get my fridgeabator made, perhaps I'll take hatching to that next level.I don't know of anyone personally that actually lowers it at hatch. I have only seen it suggested in one place of my readings as well. I don't think it would matter either way.