In Dublin we have a bit of a mixture of newish bus routes which largely have a sensible number of stops, and ancient routes (the oldest evolved out of tram routes laid out in the 1870s), which tend to have a stupidly high number of stops, because once you put one in it's very contentious to remove it. The super-regular stop routes are _so slow_.
I'm also curious how bus stops interact with timed lights. Presumably each time the bus stops, it gets kicked back to the next cycle of green lights (which might be a low-single-digit minute delay).
Hopefully there's a traffic engineer in the audience who can give the real answers.
Of course this has limits on density of traffic lights and traffic isn't fully predictable either, but overall this works quite well, giving busses mostly a green wave.
Two problems - for one, riders entering and exiting takes time, especially if the public transit scheme says you can only enter at the front and have to show/buy tickets at the driver, and the other problem is that in most areas, buses cannot request a green light, so with a loop time of 1-2 minutes (quite common in German cities on busy roads) you may easily lose 2-3 minutes in the worst case just from a mismatch of departure with the light being green.
And over the course of a few stops, that lost time can add up quickly.