Practice Drills

Here in Wisconsin my practice time is limited to about twice a month at the heated range nearby.  I have been trying to structure my time there so I'm not just wacking away at balls.  I've got several drills that I know and like to do.

My general question is should I spend a short amount of time (maybe 20-30 balls) on each drill, and do more drills from my list?  Or, maybe pick a only couple of drills and spend more time (ie. hit more balls) on them?  Or maybe it doesn't matter that much?

Also, does anyone have experience with an impact bag?  I'm looking for ways to practice in my basement.  I can chip and putt down there, but anything I can do to work on my full swing without actually hitting balls would be nice too.

Thanks in advance for any responses.

How about a winter focused on Yoga and really working the core!!!  Strong,Quick, loose muscles and a strong core to open  up the spring season.  Momentus heavy club  along with some putting on carpet and maybe a few chips  per day.   Try the super slow swing, the one that takes 1:30  to complete.   Read a few books and prepare mentally.,