And I'm just the opposite. My dogs wear their collars pretty much 24/7.
After Ilka got her teeth caught in Leo's collar while they were playing (and yes, it was a pretty terrifying situation), I would take Leo's collar off right before we went outside, and put it back on as soon as we came inside.
Needless to say, a slip (choke) collar or a prong collar should NEVER be left on a dog, but should be removed immediately after a training session is done.