Keep in mind-you should reserve what you want/can as early as possible, there is zero reason to wait for day of IMO. And time of year will matter as well like LT just mentioned.
My goal was simply to see what was available in early March since we were there, and was truly amazed actually-but these were for 2 or 4 only. However-we had 9 AP MB's in our account on the APP and would routinely grab 6 during the week for very good headliners in whichever park we wanted to plan. Were only able to use our bands though. This means TOT and RNR was always available (we prefer RNR over TSM) but TSM is tougher, Soarin and TT were easy-AK was always wide open, MK wide open for the mountains really just tougher for 7DMT and A/E.
Nothing has been more amazing than availability XMAS week though, still can't believe that one.
All they need is more attractions/capacity for the busier weeks IMO-the system is awesome when everything is available. Plus they could start bumping up the QTY.