It's probably okay to drive pedal-to-the-metal on major routes, where it's 5-10 minutes between each bus. In all other cases, however, your potential gain is a couple of minutes, and the person connecting from another bus or simply hopping on in the middle of the route might end up wasting an hour waiting for the next one, even if they were perfectly on time. I'm from a city which is a lot like Berlin, now living in a region where only point A departure times are guaranteed, and it's beyond frustrating.