Sometimes. It all depends on how many busses are running and crowds. We haven't stayed at ASMu, but have at ASSp and ASMo. At both resorts we didn't share to the MK...and I don't think to the other parks in the morning when the busses were fuller. ASSMu is the second stop for boarding so if the busses do share you have a good chance of getting on...and you are the second stop for getting off (duh). Really the busses seem to get a bad rap, then again we haven't has to wait for them in the rain or blazing FL sun/heat.