I work to many hours and cant afford to be sleep deprived at work,
i usually play for a solid 6-10 hour session on one of my days off,
hang out with mates, go for a spearfish or a bodyboard on the other.
(my days off are during the week always, not alot of night stuff to do)
As for during my working days, i dont really like playing tired,
i probably only manage 1-2 sessions for an hour or two.
I have been known to spend both my days off playing in the recent past, but i like to get out of the house. =P