At our field we have flight boxes along the flight line. It's one of the best ideas I've seen since coming into the sport. Not to get off track, but each of the four boxes is color coded. When you pull your transmitter from the impound, you post your frequency pin along with a card that matches one of the boxes of your choice. Four planes in the air at once isn't too bad. It all depends on who's flying what. We normally have a student in the air thru-out the day. They fly the pattern, maybe a figure eight every now and then, at a consistent altitude with the buddy box. What also helps is our boundaries. If your student is flying the pattern, another member stays fairly high, one will stick to flying perpendicular to the normal pattern at the downwind end of the runway, until the fourth guys shows up it stays pretty calm. When four are in the air you just need to fly conservative. A shout every now and then to let each other know your intentions is just a courtesy. I've yet to see a midair, or a struggle for landing room yet. Comes down to that courtesy and flying conservative when the sky is full, having reliable equipment meaning dead sticks are few and far between, and patience for the different skill levels of the flier. Sometimes a beginner is more of a nuisance than the accomplished pattern pro, and sometimes vice versa. When it stops being fun, that's when something needs to change. That's what the hobby is all about.