I don't follow the plans. Things that are very important to us are: ADRs for dining (free dining trip), entertainment schedule (don't want to miss certain shows, so we know to be at that side of the park at a certain time), and getting to the park before it opens.
If you want the MOST flexibility, be at the park before opening, even for an am EMH if you are onsite, and get parkhoppers. That gives you so much more time. The morning of an am EMH at MK, we got there at EMH opening and did 11 things by 11 am. After lunch we hopped to Epcot, and it was almost empty.
I'm structuring part of this trip a little more than we would like so that my ILs can see a lot before they leave. After they leave, we're winging it. Within our ADRs.
Another piece of advice - Don't save MK till the end as is mentioned in the UG. I made that mistake the first trip. That and not hitting all our priorities early in the trip. 2 of our kids got stomach flu the last day, and we only got to see less than half of MK that trip.
If there is something that is a priority to you, do it early in the trip. You can always re-do it later on!
Don't stress! If you are asking these questions, you are already miles ahead of the uninformed traveler and will have no problem at WDW!!!
Happy planning!