More specifically:
- Buses to the parks pick up at the resorts until each park's closing time, including EMH and hard-ticket events like Mickey's parties.
- Buses from the parks to the resorts run until the last guest leaves the park, or the Rainforest Cafe from AK.
- Buses from the resorts to DTD run until at least midnight.
- Buses from DTD to the resorts run until 2 a.m.
(I've been told that at some point after midnight, DTD stops sending buses to the resorts except when there are guests to take, but I can't confirm this absolutely.)