There were always certain times of the day when one bus or another was packed to capacity (the literal "sardine can"). This usually happened when school let out. I will always remember the #28 in particular. Many a bus would arrive at designated stops with people practically dangling out the windows. Some buses would stop, and a few more folks would cram on. Other times, the bus would just whiz by. One never knew if the Muni had added some extra buses or not, to pick up the overload, so you just waited and hoped for the best.