Re: Donny Gruendler here!
I appologize for my late reply -- It has been a very busy summer here in Los Angeles! In addition, you have asked one great question! (It is one that I answer quite a bit for my students at Musicians Institute as well).
With this in mind, I believe that if you are organized - you can accomplish quite a bit in an hour of practice. Thus (and if you only have an hour to practice), I suggest that you work your fundamentals.
This would include timekeeping (in both triplet and straight 8th based grooves), followed by reading and any independence issues that arise from the previous two. This way you are working on things that will help you directly - for both recording and live performance. Furthermore, and when you have extra time (after working on your fundamentals) - you can reward yourself by playing to your favorite CD.
I hope this helps.. I could write and talk about this for hours! Please feel free to write or email anytime with additional questions or concerns.