I'm in Europe and haven't experienced the US public transportation system, so I can't offer an opinion, but in my country the number of stops seem to have a negligible effect on the average speed.

Most of the slowness comes from traffic. Where there are bus lanes, the bus can even be as fast or faster than a car. Some of our trams stop every 300 meters or so, but since they have dedicated lanes, they are pretty quick. Some of the stops are at intersections where a car would also wait. When the timing is right, and most often it is, the trams don't waste more time than would've been wasted just waiting for you turn at the intersection.

Where there is a bike lane parallel to the cars, busses and trams, an electric bike with 35-40 km/h will usually be the the fastest method of transportation, especially if you cross on reds when there's 0% chance of a car hitting you. I'm talking about a busy main street with lots of lights and traffic, not a highway, of course.

Busses with no dedicated bus lanes are slower than cars, because cars are quicker to maneuver and accelerate when needed. I think if out city made the busses (and trams, and trolleys) 2-3 times more frequent, most people would use them. It would be a difference of driving in traffic for 1 hour vs sitting in a bus reading something (or doom scrolling) for 1 hour and 10 minutes. Shorter stops means less walking, so it would incentivize people to use the public transportation more. The benefits are obvious - less traffic overall, less pollution, less energy used, less road rage, more time to chill, and so on.