in last 39 years I have found some of the Other things that can affect the decision to punch out besides lack of remaining air in lungs. I'm not particularly proud to have found some of them, but I am still here and still paddleing through some degree and combination of skill, determination, or sheer dumb luck.
broken bones - amazing how distracting and limiting things like a broken nose can be, or broken ribs, fingers, or collarbone.
Dislocated shoulder - never happened to me but I've been there for others when they did theirs. K1ers rarely roll with dislocated joints, C1ers almost never do. Have dislocated two fingers, and jammed two others which can also be distracting.
seeing a significant strainer downstream - Can be an incentive to roll, but can also increase the get out of here now and let the boat worry about itself syndrome.
Knowing you are imminently about to go over a really bad drop or series of same. If you can't get it back up, sometimes, (not always) it seems preferrable to get out and assume a safer swimming configuration, AKA the rocking chair position.
Knowing you are about to go into or have already gone into a real keeper of a hydrallic that you might better swim deep out of. Almost always last resort. Did once after over 5 minutes being pummeled in hole and thought it preferrable to being rammed out by raft. Later saw kayaker run over by 3 rafts and still stay in hole. Boats come out of some holes easier with out a driver in them too as a consolation for having to swim.
gear failure - Nothing like having the boat develop a serious structural failure beyond the simple puncture. Rule of thumb - when you see your float bags going downstream faster than you are, if might be time to punch.
Another occasion is when your back band slips and you fall out beyond the seat and can't pull / twitch yourself back in. Haven't managed to roll sitting on the back deck yet. Not saying it can't be done, I'm sure someone can, but I can't. Did I mention that I NOW have a new wider gripping back band and have added another inch of minicell to both sides of the hips areas of my boat. Cut a 3\" block of Minicell into an\"L\" and glued it in to give me more of a ledge to lock my hips under. Not TOO tight to get out of, but coming out is not accidental anymore.