Yes. It's West, North, East, South. We used North. Two times in a week the bus skipped the South Depot after the East Depot and went directly to the park, because the bus was already full. But there are always more busses coming. The monitors will tell you when the next bus is coming for each park, and in the mornings, they averaged 10-12 minutes between busses to each park. If it says 12 minutes till the next MK bus, you just missed one.
Some people need to worry about getting a seat, but we are able bodied and ages 10-47 in our family, so we always stood if the bus was full. We used North because it was closest, but there usually were seats when we got on.
It took roughly 30 minutes from arriving at the bus stop to scanning in the park for Epcot and DHS and 45 minutes for MK and AK.
Portorleans.org is the best source of info if you haven't looked there. Great info on the bus and boat transportation.