If you are trying to go resdort to resort, it takes much longer than you can expect.
Youhave to go to a theme park or DTD to transfer
I do not recommend going to DTD to transfer. You end up making 2-3 stops at DTD and then if the water parks are still open, you end up stopping at Typhoon Lagoon.
Also, if you just missed the bus, you may have a 20 minute wait at the bus for the next one.
Once you arrive at the location, depending on where you are eating, it may take quite a while to get there too. From the bus stop at Epcot to France, Iwould estimate a 30 minute walk. You have to get into the park then all the way to the back.
So general, from resort to theme park, budget 1-1.5 hrs to allow for delays, entry into the park and then getting to your destination.
For resort to resort, depending on where you are, it can be 1-5-2 hrs worse case scenraio.
It is best to try to be at a park closest to your resort destination. So if youa re eating at the Poly, try to be at the MK that day.
Taxi's can also be your friend.

Especially on the way home when everyone is extra tired