To add to Diane's post ( just trying to help)
Park buses stop after the last guest has left the park (park is clear) This is usually 1.5 to 2 hours after park is closed but may not be.
Simple fact. If you are the last guest to leave the park and it's 2.5 hours after official closing, there will be a bus there for you to take you back to your resort.
Park to park buses run until both parks are clear. If AK closes at 5pm and MK is open until 3am (bus at TTC) that bus runs until MK is clear (hopefully by 3:30am but again, however long it takes)
DTD buses run from the marketplace until 12 or 12:30am depending on marketplace closing time, then all buses are out of PI. The last resort pickups back to DTD will be between 1:15 and 1:30am. The last buses from PI are 2:00am sharp. (this is a change from the operating PI days)
I'm rusty on opening times as I have not worked a morning shift for almost a year but early buses start between 6:15 and 6:30am. Marketplace buses start dropping off at MP around 9am and PI around 11am. Morning DTD buses drop off at TL first then MP and PI (based on above times) Afternoon DTD buses pickup at MP, then PI and finally TL before going to your resort.