I’ve worked in all sorts of performance disciplines. Comedia dell’arte, High clown, low clown / children’s ents, improv, film, theatre in pros-arch, round…, puppet , Grotowskian devised theatre, Boalian Theatre of the Oppressed…
Only one small subset of that work demands word-perfect adherence. Performance is much more than post-Stanivlaskian Aristotlean drama.
Even Beckett, who was completely, insanely anal about everything from the design of the tree in Waiting for Godot, to the size of the spotlight in Not I, to the length and timing of the tapes in Krapps Last Tape, still made on-set changes right up to the performance.
Not to mention, often on set the script supervisor will sometimes give you last minute changes between takes.
Then, no script is ever perfect. I did Glengarry Glen Ross (which is suuuper tight in terms of interruptions, e.g.
A: “And a man has to shiver in his…”
B: “…shoes…”
A: “…boots…”
B: “…shoes… boots…”
A: “…And for what?” )
But one night the cop missed his cue during one of the sections where people are coming in and out of the office to be interviewed, and I’m (as Roma) trying to put the screws on the guy from the Chinese restaurant so I have to keep vamping on convincing him not to call his wife until the cop remembers to come out and confuses him for Shelly Levene.
It’s so much better for the audience for me to vamp than it is for us to stop the play and go and tell the actor he missed his cue. The show must go on.