I arrived at the stop eight minutes before a bus was due, only to watch helplessly as one pulled away. Annoying, yes, but maybe that was just the previous one being late. Eight minutes later, no bus.
Twenty minutes after that, the next bus came along, right on cue. It turns out that I missed my original bus because I was only eight minutes early for it.
I don't know why they bother actually printing timetables. I can understand a bus leaving a minute early or so, but eight?