@Cathy492 When you block a date, you are really blocking nights. So a guest that checks out on a Sunday, if you blocked Sunday, that would block another guest from booking Sunday and staying Sunday night, but I don't think it would afffect the Sunday check-out.
I don't really understand, if you say you have back-to-back bookings, why you'd block out any dates? If you want a day between bookings to clean, under Availability settings, check one night before and after. It seems like it should only be one day before, but if they did that, then the day and night of a check-out would show as available to book. So in fact, if you choose 1 day prep time, the day and night after a booking will be blocked, and someone can book the following day- the "day before" prep time for that reservation becomes an overlap with the "day after" the previous booking.
It took me a long time to figure this out, as why would we need a day after a booking to clean, we only need the day before?