We don't hit all the parks for that...
Last trip we did hit Epcot and Magic Kingdom for shopping last minute things ... along with a final run on test track and Big Thunder.
So .. as I read the question as hitting all four parks ... I have to say go
I have gone to all 4 parks in a day. I was shopping for a certain kind of sweatshirt, and never did find it. Being at 4 parks is not hard, but the worst part is walking from the buses to the entrance of each park. You put on a few miles just getting to the parks.
So, here is my question:
What's your favorite thing to do at WDW?
Mine is people watching and soaking up the sunshine.