It may stay on longer than the amount of time it takes to renew. Perhaps for every wake it stays on for 60 seconds; it is also doing other things like checking mail.

I wonder if some user-space process lights up and throws a wrench in things.

I’m sure both Microsoft and Apple have entire teams with incredibly full backlogs dealing with power management. And I’m sure half their time is spent dealing with “messes” caused by other teams doing wild and crazy (but somehow theoretically useful) shit.

It’s clearly not an easy problem.