I see what your saying. Instead of having Q mains beceuse you have so many people running 3 classes you'd have only out to G mains if the races were longer and people ran 2 classes instead of 3, and they would still get just as much race time. But would people limit themselves to 2 classes or would they be greedy and stay in all 3 classes to get 120 minutes of race time?
Makes sense. But at the club level, especially on weeknights, the number of heats would not likely change. The longer quals would make it hard to finish things at a reasonable hour.