I don't think there is such a thing as interviewing for the waitlist. If you kill it at the interview and they want to admit you, they will admit you, and that will eventually be offset by one less waitlist offer going out when those start up in May. All schools that are still interviewing will still have this buffer set up right now. It would be very self defeating for them to offer so many early admits that they can only waitlist candidates they want while their cycle is still going.
Now it might be true that more people get waitlisted at the tail end of the cycle, but that's because of the
LizzyM staircase analogy: the cohort that barely snagged an interview in the last passes through the app stack is on average going to be further from the admit threshold. That might be a legit concern. Worrying about the school already sending so many admits that they
have to waitlist everyone they like, not so much.