For revolvers - always five shots.
I have five-shot and six-shot DAs and always shoot SAs as five-shots, even if they are New Model Rugers.
It's not that I don't trust the transfer-bar system, but it's an old habit, for one, and a box of fifty yields ten of five shots. For the six-shot guns, I always make sure I'm not skipping the same chamber each time and I fire multiple groups.
I always load multiples of five as well, like five, ten, twenty, etc. When first checking to see if a particular gun is happy with the pressure, I'll load ONE at a time, but just shoot it into something which will retain the projectile - into the ground, a log, a stump, maybe even the back stop.
Not that this is right or wrong - it's just what I do.