There isn't really a "policy" about resort hopping, although you aren't allowed to use the pools at other resorts. There aren't really any buses designed to take you from resort to resort, but it's still pretty easy to see a lot of hotels without much trouble. Say, for example, you want to see the hotels on the monorail loop. Hop a bus to MK, and then get on the monorail, or walk to the Contemporary. The monorail will take you to the Poly and GF. To see YC/BC, BWI, and S/D, go back to MK and get a bus to one of those resorts. You can walk between them.
If you want to go to any of the resorts that are more isolated, you'll need to go to a park, get a bus to that resort, and then get transportation back to a park to get back to your hotel. Make sense?