A-320 roster:
-Days off: ...8 days.../month.
-Flight time: ...70 hours..../month (..750H.../year).
-Layover:no general rules ... 3...4.. /month.(might be sometime less. might be more..)
-4 sectors a day...not that much (in my case..).. 1/month...?
( i have seen people with 4 ..5 /month).
-yes we do fly 319-320-321.