I agree. I know what is given as the standard, but it is just not my experience. I think they are more active, eat better and grow/feather faster if kept a little cooler. Around here, people have for many years put new chicks in a coop with a 100 watt bulb from day of arrival. If they piled too badly, the bulb would be lowered. They may have lost more, or not, but the survivors were healthier, I feel.
I brooded two batches in my house but did not keep it much over 80 in the brooder after a week or so, and I got them into the coop pretty early. But I will not brood in the house again. I will find a middle ground between dumping them in a cold coop with one light bulb, and filling my house for weeks with dust that I should not be breathing.
But I wouldn't use the conditions they endure during shipping as a standard, either. Yes, most survive, but it seems to me it is barely so. They often show signs of stress and require some extra attention to keep them alive and get them started. Chicks hatched under a broody will eat and drink early. They will also go outdoors on a 50 degree day at 3 days, though they run under Mama every little while to warm up. (personal experience there.)
If the chicks pile, they are too cold. If they cuddle and huddle in one layer, they are just being chicks. It is said they will move away from the heat if it is too hot, but often brooders are really not large enough to allow for much temp difference. And I'm not sure they can be depended on to do this, anyway. If they get a little too warm, they get quite lethargic, and I don't want to trust them to move away, even if they can.
Even at 80 on day 7, many of my chicks moved to an area of the brooder that was separate from the area heated with the heat lamp. I had an L shaped cardboard box setup, the long side the size of a refrigerator, with the heat at the top of the L, for 50 chicks. About half would sleep on the other end of the L, away from the heat.
Long speech; sorry. I really do think we tend to bake them, though.
