I think it takes MORE planning to make a plan that can allow you to adjust well on the fly, vs. strictly following a set touring plan.
The more times you've been to a park recently, the less you need a fixed plan, as opposed to "Start in Tomorrowland, use our first three FPs in Fantasyland, and then see where we want to go."
If you have a good sense of all the rides and the general wait times and distances, etc., that puts you in the best position. For example, what if you have a FP+ for Winnie the Pooh, but it's down during your window (honey explosion, it happens)? You get an anytime FP to ride it later, but then you need to decide what to do next. You're in the middle of Fantasyland at noon. There are some good choices and some terrible choices, and it's no fun to stand in a huge crowd trying to decide which way to go.
We have two young boys. If we said to them, "What would you like to do next?" it would be a disaster. But there are times when they need a high-energy ride, and other times when they need to relax and be off their feet for awhile. And so on. So we definitely adjust on the fly, in any park. It's better to hang out in the Boneyard or go get a smoothie than deal with a meltdown just to stay "on plan."