During my time in the huge group mentioned above, I never once met availability problems. It was only a C152 and I think that over 50% of the members never flew it. In my experience in about 5 different groups over a 35 year period that is par for the course. My present group has only 3 members, one has not flown for well over a year and I only did about 5 hours in the last year. So the one guy that does fly often virtually has it to himself.