I am thinking that, despite having run shuttles in Orlando for decades, Mears is going to have learning curves and growing pains and fine tuning to do for Mears Connect.
At least 2 reasons. The existence of Uber and Lyft will change the demographic of folks using shared shuttles, like cutting down on the number of large families and requiring more stops to fill a bus. There is more traffic overall compared with 10, 20 years ago.
I would suggest that for at least the first half of 2022, you make your return to the airport for 4 hours before your flight, maybe 3-1/2 hours if you feel you are faster than average folks in maneuvering through the airport. Otherwise I think you will be anxious during your ride.
I would even question the premium (express) offering. It proposes a resort pickup 2 hours before your flight. You need to be at the airport 2 hours before your flight, otherwise there is a good chance the first few zones will be boarding when you get to the gate, and running for your plane is a distinct possiblilty