On the 737 I would say 12-13 days off while on reserve, depending on how many days in the month. Once your a jr line holder it will depend on how you bid. If you bid for lower line values (70-75hrs) I would expect to average 15-16 days off. Maybe 13-14 if you bid for higher line values.

I started holding partial weekends around 65%. Complete weekends around 50%.