I do it often, I don't plan it, it just happens. I'll start my morning in park #1 and hang out there until around noon or 1 and maybe grab something to eat. Then I go back to my resort for some quality pool/rest/nap time. I usually leave my resort around 3 or 4 and go to park #2, which more often than not is Epcot since there is usually a festival going on and most of my non-breakfast meals come from the booths. After snacking and maybe riding a ride or two, I'll hop to park #3. Since I'm not a planner and never make anything other than part reservations in advance, if I want a sit down meal, I'll just grab that during the day. That will sometimes determine what one of my hops will be. I tend to do split stays with the first night or two in a value or moderate then I switch over to an Epcot resort.
Example I'm staying at ASMov for 2 nights then switching to Dolphin for 4 nights. I drive down from north Ga. and usually arrive between 1 and 3. On arrival day I drop my bags in my room if ready and go to Epcot to eat. After I've snacked some and ridden a few rides, I usually hop over to MK, which is normally where my first full day reservation is because to get there from Dolphin you are dropped at TTC but from All Stars you go to the entrance. I might spend a few hours at MK and either hop back to Epcot or retire for the evening.
1st full day maybe grab some breakfast at food court if I'm up early enough or go ahead and go to MK. Do whatever at MK until around 12:30 or 1 then go back to the resort and rest. Since I'm at a value resort, not much to do so around 3 I'll hop over to AK and grab a table at Nomad Lounge then spend a few hours riding a few rides like Navi and Dino. Then I'll hop to HS cause I love it at night. I might ride a ride or two or just shop.
Day 2 is an AK day (remember I was there the night before and knocked out a few rides) so I go eat breakfast load my car and check out since Safari doesn't open until park open, no reason to get there early. I'll ride a few rides, watch some shows, shop around and leave around noon or 1. Go move my car over to Dolphin. Go to Epcot for something to eat and maybe ride a ride or two. Hop over to HS and ride a ride or two.
Day 3 is probably a HS day, I've already been there two nights and knocked out a ride or two so not in any hurry to get there unless I want to ride RoTR, sometime I do, sometime I don't. Ride a few rides, grab a table at HBD lounge and leave around 12:30 or 1. Go to the pool for some quality hot tub/refreshing adult beverage time. Around 4, after showering, I'll go to whatever park suits my fancy. I might just do a two hop that day. I've already done 3 afternoons at Epcot, a morning and evening at MK.
Day 4 and 5 are just do whatever days. I'll most likely have my reservations at Epcot one day and probably MK another but who knows what I'll do after two those days.
That was just an example, I really am pretty loose and just go where my feet take me. I've been known to do 4 parks without even trying. I only use Disney transportation even though I have my car there. I've found that by going to the park at night that I've got reservations for the next day, usually takes some stress off the OMG I have to rush around mind set. MK is my least favorite park, I only have a few must dos there and try to catch at least one parade during the week. I might or might not do the FWs there. Since I'm height challenged the projection based ones aren't much fun for me but I might find a spot off to the side somewhere so I can just see the FWs and see Tink fly and I'm good. I love the Epcot night time show and try to catch it at least once and when Fantasmic comes back, I'll be there.
