Before there were blinking displays, Muni schedules were a chalk board affair. From Market Street Railway, here’s Muni’s first schedule, for the inbound A-Geary in 1912. If you look closely, you’ll see that the times are stated to the nearest half-minute.
According to Market Street Railway:
Eight cars were scheduled (Muni only had ten on hand at the time). It took 28 minutes to go from Tenth Avenue and Fulton Street (Golden Gate Park) to Geary, then all the way downtown to Kearny and Market Streets. Today, the schedule for the 38-Geary is about the same to run from Park Presidio (near 14th Avenue) and Geary to the same point downtown, about the same distance.