It varies due to the stupidity of those who run the buses.
Next Bus is a better App once you learn to navigate it. Usually during the day it's every 30 minutes but night owls and peek hours are different. Google Maps directions gives a pretty precise immediate time frame and most people already got that one on their phones.
It varies,due to traffic
The times for the buses varies. It is nearly impossible to point out when exactly will it arrive. You can download Muni app,or use google map to get the time of arrival for the next one.
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