I actually use 10 and I get perfect stats. I do tend to eat up a lot of clock on offense though, but the last game I had I had 128 plays. Usually I end up with about 60-70 plays a game which is pretty realistic especially with no huddle teams.
Same here. With 10 minute quarters I usually get around 130 plays. I couldn't be much happier with the stats. The lowest play count I've had is 122, and the most was I think 148 (a game against SMU where we combined for 99 pass plays and 40 incompletions). I usually take my time snapping the ball (usually no more than 15 seconds on the play clock unless I'm in hurry up or something).