I know the thread is a little stale but I want to throw my 2 cents in as a new shooter.
It seems to me these gun game sports is a practical way to shoot something more situationally applicable than a B-8 @7, 10, or 25 yards (which I enjoy plenty). I know it's not a real life gun fight but it certainly entails more skills than my monthly bullseye match. An artificial round count might have been initially set by the Clinton magazine band but since that has gone away it remains useful to force a mag change. Mag changes is a skill set that needs to be practice to maintain competency, just like grip, trigger control, sight alignment, etc ...
The sport is about applying skills to build muscle memory in the event you may need to use said skills under duress in real life. Who cares if the mag change happens at 10 rds or 15.
Per the spirit of the sport a stage should require shots accurately on target, while being mindful of cover, and include a mag change. Use time and accuracy to asses a players competency. Create a rule set that everyone plays by to establish parity and you have a sport.
My 2 cents.
M