You are limited to two active waitlists per use year.
Each booking category counts as a separate waitlist.
Thus, for example, you can't waitlist "Animal Kingdom"...you have to first choose between Kidani & Jambo, and then between std, value & savannah...
You also cannot do day-by-day...so if you want to waitlist a full week in the same room, you have to do the full week--you can't break it up into shorter segments.
It's easier at SSR--no booking categories there. I don't think there are any booking categories at Wilderness Lodge either. But Beach Club had one "extra" category (two queens in dedicated two-bedroom); BWV has standard view, preferred view, and boardwalk view. OKW has Hospitality House as a separate booking category. BLT has MK view, lake view and standard view. (There may be more I'm forgetting.)
So, waitlisting is MUCH more restricted than it used to be.
Good luck!