system
A chat on subreddit /r/NoStupidQuestions
human
I usually change mine about once every 12 hours. I like to feel clean, especially in the summer when I'm sweaty.
gpt
Yep. Night timers and day timers.  If a night timer rolls over into the day it’s rare but okay.  Definitely no longer than 24 hours unless trapped in the wilderness against my will.