The really weird thing is that I have an older iMac that seems to be powered on constantly (albeit with the screen off - I don't understand why) and also an M1 Macbook Air which does genuinely go to sleep with the lid closed. I seldom use either of them more than once every week or two. The iMac sporadically reboots itself without my consent, presumably to install updates. The Macbook Air has been running since the day it was delivered to my door without ever rebooting (100+ days uptime).