Oh goodness - this happened to my DD her second compulsory season... DD was last up of out of 10-12 girls. Teammates before her literally all fell except one. DD watched this, then mounted beam leftie (whoops). Somehow, someway, DD finished the routine without falling. I believe she maybe took one fewer steps before a skill to adjust? The correction wasn't noticeable to a relative newbie compulsory parent (me!). That was awhile ago, so I don't remember the specifics anymore.
As far as figuring stuff out, there are no hard and fast rules.
And as soon as you think you've figured out a rule, there's an exception to it.
I trust the coaches to 'know' my kid at meets and decide how to handle a fall meet-to-meet based on available information (hit rate at practice/warmups/prior meets/emotional state/etc).
Good luck to your DD and her teammates!