It would be a very rare occurence for a DME bus to be assigned to drop off guests at only one resort. The max is 4; 2 or 3 are typical.
There is no pre-set groupings of resorts, and no set routes. It's all dispatched and arranged due to need. There's no way to know in advance which other resorts you'd be on a bus with, and what the drop-off order will be.