Sorry, but I dont understand how loading only 5 rounds does anything for safety. And if you just loaded a full mag, just take it out and put it down. You could also just keep one in the chamber and then load a mag so youll have 6 lol
The range commands at cease fire are to complete your firing, not to eject your magazine and your chambered round. I understand it's 6 in one, half dozen in another, but the range sets the rules, and the RO's give the commands.
I've done a ton of research on why certain ranges set their rules the way they do.
(1) The consensus of most sources I found as to setting an arbitrary maximum number of rounds loaded in the gun is .... it's the range's rule! It is what it is, and that's the game you have to play.
(2) As for emptying the magazine & chamber by firing the ammo vice removing a loaded magazine and manually clearing the last round in the chamber, the consensus is: at some point, there was an ND (negligent discharge) by some untrained or careless shooter. So, the range came up with a lowest-common-denominator rule: it's safer to clear a gun with no live rounds remaining in it.
I'm not arguing for the rules in either case. That just happens to be what I've been able to dig up on the question "WHY?"