"The more I watch those babies outside perfectly happy, the more I think we backyard chicken folks have been sold a bill of goods with the whole "needs a heat lamp" and "95 degrees for the first week" thing. Because no. And not true. "
This is one of the things I can really get heated up about, pardon the pun. And most people readily and eagerly accept the heat guide as scripture. Just watch day-olds romping around an outdoor pen on a 60F day, not spending much time near the heat source. People have a need to follow specific directions because they doubt their own powers of observation and ability to make judgement calls when this would be the better approach to judging the heat requirements of their chicks in their own individual situation.
I live in North Texas, ordered 10 chicks, have a shed as a coop with windows open and have had chicks with no heat. They have been healthy and happy since Friday.