I voted 6-10 - because I don't actually game that much on average. I have a LOT of minor sessions, testing games and then being distracted. For the most part, I don't get anywhere near completing them these days.
However, once in a blue moon - a game captivates me and I play it a lot. I'm single at the moment, so I can dedicate pretty much the time I want to gaming - but I'm struggling to play long sessions even so. Usually, I play a 2-4 hours each day when there's a great game holding my attention, but that happens rarely. Perhaps once each month or so.
However, when something REALLY captivates me - I can go back to how I used to be, which is playing 6+ hours each day until I'm done.
Last time I did that was probably with X-Com 2 and Mankind Divided. I think I completed those (separately) in less than a week each - spending 40-50 hours on them.
Incidentally, I'm having a similar experience with Prey right now. I never know when something will keep my attention, but this has a very good chance of doing just that.
Also, I've taken a week off for both Prey and to experiment with ways to deal with my current health issues.