For us it's all relative to the season, crowd level and your touring style. We can do the MK, 1/2 morning and return for 1/2 evening and just about cover it, but we go value slack season but spend another day there as well. AK, which we do not care for is 1/2 day park and EPCOT takes a day and a half and DHS a full day. We take afternoon breaks, hop to a different park than what we do in the am and again, we're on property 1-12 nights, usually have AP's so jumping to the park with the latest closing is how we tour. We most always stay in the MK resorts, WL, and pop into the MK on a whim.
No commando style for us, when the crowds thicken or the heat builds, we leave, resort swim and relax and return when the sun goes down. Everyone has their own touring style, some stay in a park opening to close, long day, we enjoy our resort too, so allow for time to play, swim, walk and dine. It's also according to your family, how many small children and their stamina. After you're into a couple of days, the old legs protest and the feet get weary and pushing it from their will make for a miserable vacation, just go at your own speed, you'll never see everything anyway.