For me it depends. If I wore a shirt just to go out and grab my mail, I’ll probably wear it again. Quick trip to the grocery store when it’s not hot and I didn’t sweat? Maybe wear it one more time or use it for getting the mail. If I wore a shirt all day, leaned or sat on public furniture that likely isn’t cleaned regularly (i.e. cinema seat, restaurant chair, plane seat), or was in a crowded place in close proximity with a lot of other people (i.e. concert); that’s definitely one wear and goes straight for laundry when I get home.