Well, usually during the week at night, 2 to 4 hours. During weekends I don't usually play frequently. But I have to admit that what's limiting the amount of games I buy right now is my free time instead of money. I don't like to buy games that I won't really play. It already happened, but at least 80% of my games were finished and most of the others at least got a decent play time.
The only games that I find acceptable to not get a lot of playtime are PS+ freebies, since I didn't paid or actually chose them. The ones I do like get a bunch of playtime.
I would say that online MP games also keep me from finishing more games. I've put considerable time in Uncharted 4, Battlefront and TLOU in the last few years. I'm getting on Metal Gear Online now and it's pretty great.