After reading everything that made it sound complicated and nerve wracking to plan ahead - I reached my 10 day mark. I never fall into the "need to be the 1st to book" nor do I worry if something isn't available. To be fair I go several times a year and rarely, if ever, ride any thrill rides/coasters.
I got on the app around 10:30AM Eastern - I had a list of where I'd made Annual Pass daily park reservations and just started out for my 3 reservations at that reserved park. Every thing was available - I could have scheduled individual rides and all of the popular ones. Granted - I'm 1 person, and had 10 days to choose from. WDW is my happy place and I just can't stress about what I can't or can experience. I was very happy