So here's a question. Obviously in games like War Thunder, you keep on fighting until you're deadified beyond anything. Full loss of crew, for starters; what happens in most cases when a tank takes a penetrating hit and doesn't end up with a mulched crew that tries to push the headless body of the gunner out of the way and go back to battle? At what point is it acceptable to bail out of a tank, especially older machines from older wars? Nowadays, I understand, the things are so robust that mission kills mean you just sit around and protect the tank until recovery crews show up, but what about in prior battles? What's the expectation, and what's the typical history, for the crew when they get a serious hit? Not counting ammo explosions or fires where the whole crew's obviously dead, of course.
From my understanding, post-WW2 tanks don't have "spare" crew - everyone has a vital role in making the tank an effective combat unit. While you might need to finish an engagement the loss of the crew member (doesn't have to be dead, just incapacitated) would mean it would be worth pulling out of the battle fairly quickly for replacement.
The crew can be thought of as three parts, either with three or four crew depending on whether or not there is an auto-loader.
The commander provides the situational awareness - often sticking their head out of the turret and so may well be the one lost to a sniper, shell fragment etc.
The gun crew provides the firepower - while the commander might be able to take over either the gunner or loader role they would then still lose the commander; this might be adequate if the tank is retreating and laying down fire fairly haphazardly to cover this but in any sort of attack would be bad.
The driver provides the mobility - without this, you just have an expensive pillbox.
At the risk of sounding like you are de-humanising the crew, consider them as components in a machine the same as the guns, engine, tracks etc and then consider when you would pull out of battle versus carrying on.
In terms of when "penetration" occurs, I wonder what would happen with a Western tank without auto-loader and with the ammunition kept away from the crew - would some at least stand a chance of survival despite the presumed spall and other badness that would occur due to the penetration from a kinetic energy or explosively formed bit of metal making a surprise entrance into their living space?