A lot. I've done it with 5 or 6 in Nome and Kotzebue. You all have to agree to provide visual separation with each other. The frequency gets real busy as everyone chimes in, "I concur" in sequence to each additional request to maintain visual separation. It also gets a little busy if you are all holding outside the zone and get cleared in at the same time. Sometimes you would join other planes in the same hold at the same altitude and follow each other around the race track VFR. Then when you got cleared in, you were already lined up.