Sure some schools use predictive analytic models at the applicant level, many don’t.
Either way a college would have to be far off its yield projections/tracking to go to the waitlist before May 1…and some schools are concerned that their models might not be too accurate this year. And remember information is far from perfect…historically important yield variables don’t apply this year, such as distance traveled to visit, nor do most students who accept elsewhere decline their spots at their other admits.
I’m sure some colleges will have to go to the waitlist early, same as we saw greater numbers go to waitlists before May 1 last year, but many will wait until after their deposit day.