Off season is better. Stay away from 3-day weekends or near holidays. We did mid Nov and almost walked on everything. Did a couple of Sundays ago and POTC was a 30 min. wait.
They are the weekends in January and February after the Holidays and before Presidents Day Weekend. These are the weekends where instead of 8-12 hours, they get 9 to 11 or 8 to 11.
This year people reported the opposite. I think either the secret is out, and/or it alternates (as in, this year it was so crowded people will remember and avoid the parks next year! ).
Though people do have different experiences...sometimes you'll read one person says a day was very busy and another person says the EXACT SAME DAY wasn't crowded at all!