The buses start running by about 6:30 AM daily, most likely even earlier if a park has 7:00 AM openings (not sure if this is still a thing). Yes, you would probably want to be at the bus stop at least 60 mins, and possibly closer to 90 mins before the park opens. This allows for you to have just missed a bus, resulting in waiting another 20 minutes to get picked up, and then 20 minutes drive. It partially comes down to your desire/need to be there at a certain time and your ability to get out the door in the morning.
The worth to Uber/Lyft is up to you. Going to MK you would need to build in extra time to either walk from the Contemporary or travel from the TTC (depending on the ability of your driver to find either). The drop offs at the other parks are more in line with where the buses would leave you. Does $10-15 to avoid waiting 10-20 minutes for a bus seem worth it to you? If so, you know your answer.
And yes, Disney won't strand you at the parks. As the night goes on they may go from each bus running a single route to a bus running multiple routes, and potentially even get to the point where they just stick you in a van if you are absolutely last. Even on non-EMH nights this still happens. We had dinner at Rainforest after AK closed, walked out to a line of buses, they told us to head to the first one, tell the driver our hotel, and we were off.
