I put down five, because that's the most I've carried, but I ordinarily consider three the best number, although I usually carry two.
Three is one available to each hand, and an ankle gun. I often omit the ankle gun if my LH gun is reasonably available seated.
When performing certain duties I am no longer required to, it helped to be able to have a gun in hand without being super obvious about it. That added a J-frame to each suit-coat pocket, for five. Usually, when doing that, I figured I had enough guns for each hand, and carried mags instead of my LH (2nd) gun, but I think I probably carried all five at least once.