When I actually mess myself, I can sit for about half an hour before I really think about changing, mostly because of the smell, some because of a rash, and some because if I changed right away, and messed again, I'd be blowing through diapees like crazy, so most of the time I simulate messies with plain oatmeal, pour water in, heat in microwave for a minute or so until warm, and some water evaporates, and then let it COOL a bit before putting it in my diapee, which I can stand for about 3-4 hours before it starts to bother me mentally, and I change/clean up, but I found that when I worked one night with an oatmeal messie, I shouldn't go past 5 hours because I ended up getting a hemorrhoid, and that put off my messies for quite some time.