You are technically correct, but you miss the great part of frequent departures in a public transport system.

During peak hours I have a buss departing my local stop every 10 min, it takes me 7 min to walk to the busstop, when I arrive to the metro my train usually departs within less than 5 minutes, it takes 2 min to walk down to the platform from the bus, if I miss the train, the next train will depart 5 min later. When I need to switch lines I just walk over the platform and my train will usualy arrive with in 2 min, though it is not unusual for the train to be at the platform and I have time to cross the platform.

When I then get to my destination I exit the metro and walk 100m to get to my office, my desk is actually just above the entrance/exit of the metro.

Obviously this is under optimal conditions, but it isn't that uncommon either.

When you have public transport departures that frequent, you don't really have to took at the timetable, you just walk down to the bus stop and with in minutes you are on the bus.

There are also dedicated buslanes along 97% of the way I take the busses, so traffic jams are seldom an issue.

And should there be an issue with my normal bus, I can walk 15 min to a different bus stop with other busses, or I can walk 20 min and get to the train/bus station and get on a train or yet another bus.

This is fine since large disruptions are quite infrequent.