Currently I devote the equivalent of three "nights" per week to gaming. I play a game from noon until early evening on Saturdays (admitedly, more than a "night"). I run a game on Wednesday evening. And I easily kill another night's worth of time (in various chunks throughout the week) prepping/writing/developing/etc. for my game.
At my most "gaming-happy", I played in two weekly games, a game that met once every two or three weeks, and ran a game about once a month.