I actually did the four parks in one day about three years ago.
I Started at AK, was there first thing in the morning: Had early (8:00am) entry for breakfast at Donald's Brontosaurus: then did Dinosaur,KS, train to petting area and back (did not get off), It's a Bug's Life,, to Poccohontas, Lion King . Had ice cream on way out. Left park by 12:30
took bus to MGM (lost 15minutes having to stop at water park) arrived just after 1pm.
At MGM: Great Movie Ride, Little Mermaid, Muppets 3D, Star Tours, TNT, RRC then out of the park. Lunch was a hot dog I bought from a cart on way through park.
took boat over to Epcot , arrived 5pm
Walked through international gate straight to Test Track, the World of Energy, SpaceShip Earth, then left for MK.
to Monorail to TCC, monrail to MK: arrived at gate 7:30pm
Spent the rest of the EMH day at MK. Had Dinner at Cosmic Rays, Left just around midnight.
I saved some time as I had an annual passport and thus did not have to wait to get my hand stamped every time I left a park. Plus I was not carrying anythijng with me, thus did not have to have the security check.
Would I ever do it again. No, it was very tiring and very, very rushed. Plus there are added attractions at both AK and EPCOT which would add at one additonal hours at each of these parks.
I did really enjoy that day: there was no time to actually relax and enjoy what was going on around me.
