We just did four parks in one day during our trip in August.
We decided to set up guidelines of things to accomplish in each park to make the day more interesting. We had to get two photos taken together as a family in each park (this turned into arriving and departing photos!). Also, we had to do two rides, shows or character meets in each park. If for some reason we were not able to accomplish a show, ride or meeting a character, we substituted getting photos taken - two for each “ride” missed. We had hoped to also include transportation on a boat, car, monorail and bus, but we decided to drive as it was raining and forgo the boat.
The order of parks made sense based upon park hours for the day. But it was a similar pattern to other liners - AK, HS, EP and then MK.
We ended up going on a rainy day, and had several rides break down while we were on them (or waiting for them) and we had trouble finding photographers. But we were still able to accomplish everything and we learned we had to be a bit flexible with our plans. We were on Soarin when the film broke, and even with our FPP for the ride it was about 90 to 120 minutes after arriving for the FPP that we left the ride. This meant we arrived at MK as the park closed and Wishes had just let out. This was about 90 minutes later than we had hoped for, but we decided a ride photo (you know those three from Space Mountain) would count as a photo.
Within our day we planned not only a rest in the middle of the day at the hotel (YC) but also a table service meal. If I had to do it over again I would have planned dinner better, we managed to eat at Casey’s after Wishes, and it was very crowded! But I had no idea what other restaurants would be open during EMH. But taking some time for a table service meal may have been possible because we drove not only to AK, but also to HS.
I certainly recommend trying it - my kids DD13 and DS15 both had a wonderful time!