We have 2 1/2 days at MK. Is it best to choose a premade touring plan or creat your own? For example, right now I am working on one that would keep us in fantasyland all day. Would I be missing out if I separated the days into areas?
One suggestion would be to copy the plan and then customize it. You can delete attractions that you don't need or have time for on this trip.
Divide and conquer is certainly a strategy. It all depends on what are your MUST DO's vs everything else.
The good thing with the pre-made plans is that they tend to be well-tested. So the 2-day plans split up the park into left and right sides, which helps with criss-crossing.
Especially if you are relatively new to the TP process, I would strongly recommend using the "standard" 2-day plan as a starting point. After you have finbished your 2nd day, create a plan for your 1/2 day, including the attractions that you might want to do again (or missed for some reason during the first two days). Also, be sure to get your 3 FPPs for that half day, based on what you "think" you might want to do again...