Pretty simple. When things don't go to plan, do you reload, or see what you can do to salvage the situation? I find that usually I try my best to roll with it, and sometimes that works out, but other times I end up with a knife through my neck. But nevertheless, there is a great satisfaction in getting spotted by a guard and escaping successfully. That satisfaction isn't there if the moment something goes wrong, you reload. Of course, if you're doing a Clean Hands/Ghost playthrough, it's okay.
