1-2 hours during holidays. else 2-3hrs per week.
sometimes i also play for continuously 3 or more hours!
just checked my total playtime on steam.
it counts my playtime as 306 hours.
XqzM3 - Steam Hours Played API Calculator, Ranking and Stats
Lambent Stew : Steam Profile Analysis.
i'm sure that does go much higher since it doesn't count offline mode and non-steam games.
and angry birds, draw my thing etc also amount to much playtime if you count them.
if i have no work, no exams, no new movies in cinema and tv, then i would keep on gaming for hours.