I 100% agree this is a mega-moment in a mind blowing film, but I'm not so sure this was such a pain in the ass to shoot.
Well rehearsed choreography (via the amazing Toni Basil), a tape measure & a good deal of foresight would have made this time consuming but very achievable.
the match cuts make me lose my mind oh my god fuck them its like they're only switching the lights. can you imagine what a pain in the ass it was to make this in 1968