From a competiton perspective, trying to have more than two pilots share an aircraft at the same level in a competition becomes problematic...
At the last Dutch Open National Aerobatics Championships we had eleven people competing in Basic and Standard combined, on a grand total of three aircraft. Intermediate and Advanced combined had nine people competing on two aircraft, plus two competitors who brought and flew their own aircraft. A CAP-21 set the record by being flown by five different people for a total of 19 sorties over 2.5 days.
There basically was no randomness to the flying order as far as the airplanes were concerned. We were able to mix the flying order of the lower two classes with the upper two classes to speed things along every now and then.
Everybody took things in stride though. The competitors, the jury and the organizers. Of course it helped that the whole organizing committee flew in the same single aircraft. And the weather was exceptionally good so we were not short of time.