I'd say on or before major holidays. We've been at WDW for 4th, couple days before Thanksgiving, Christmas, New Years- packed. Jan 2nd or 3rd it slows because kids get ready to go back to school. Oddly enough the weekend before Thanksgiving in the past has not been to busy.Most popular/busiest time at the parks
Lower point seasons in lower point studios is the main target of commercial renters. 2BRs is next most popular.
That’s just for DVC. Park crowds, resort rack rates, and DVC seasons do not have matching highs and lows.