As long as you apply some powder and some diaper rash cream to your diaper area you can easily wear a wet diaper for 8 hours or longer before changing.
I've worn the same wet diaper for 24 hours before and it was great feeling and I didn't want to change but I would say that after 24 hours I was wise to change.
I started getting a diaper rash so 24 hours would really be the limit to wear a wet disposable diaper that you peed in but if you just put water in it then you could wear the wet diaper until it falls apart which could be a few days or more.
I've slept in soaking wet diapers before too and it's never been a problem for me.
But I would change the wet diaper after at least 10 hours unless you have a more lower capacity diaper that needs changed more often.
I wear thick diapers from Northsorecare as well as Abuniverse diapers and they hold up for nearly 8 hours before I change.
So I change my diaper at least twice per day with the higher capacity diapers.
I love wet diapers and stay in the wet diaper for as long as I can without changing.