I always do 7 day waitlists. If there's a small difference in points, I'd rather have a few points go into holding than have to change rooms. As I make multiple trips per year, sometimes I can save the points.
I had a similar scenario as you. I booked a resort studio standard view for 3 nights, or so I thought. I'd booked two nights than added a third night which I hadn't yet asked to have combined. A couple of days ago, I was flipping through my reservations and realized I'd booked a standard studio for my 3rd night, not a resort standard.
Set up a waitlist for 7 days before and lucky for me it came through this morning! My trip is March over Easter - the week prior and during. I move to Animal Kingdom for day 4 through 6, so 3 nights in each resort.
There was a moment of crazy this morning. An email came through saying 'your room has been canceled'. Used to be 'We can't wait to Welcome You Home'. Rushed to my account and found my waitlist had filled.
Now I'm waiting on another waitlist and I doubt I'll get it, but I'll ride with it all the way, including doing some stalking as much as possible during the last 7 days. I 'often' see rooms pop up in the last two or three days as I'm searching for vacations. Good luck to you!
PS - I'm one of those people changing things all the time.