Usually at least 3 or 4.
I play a lot of 'endless' games like racing sims, Cities Skylines and multiplayer shooters and I usually hop on these whenever I'm in the mood, which is usually at least 1-2x a week for each of them, even if for just a short period of time. So if I'm counting them, that's already 3 games right there.
And then usually 1-3 single player games. Often more than one because I like to have a fallback game if I'm getting burnt out or hit a wall(as I have right now in Dark Souls 2), where I take a break from it and come back later.