Jay, here's the way I try to work it:
7pm is instruction and rep time. I try to teach it with demonstration, guided practice, and then reps. At 8 we go to a brief Q&A concerning the tech we covered. At 8:15, we roll till at least 9:30. I expect them to step outside of their comfort zone and work on things that need work, not just look for a "win" during free roll. The students we have that are doing well in competition consistently pinpoint their biggest weaknesses and/or strengths and rep these.