Except of course people aren't going to use turbolifts for short journeys anyway, in all likelyhood will not use them to travel on the same deck, only from transfer from one deck to another.
The time saving is when the ship is called to battlestations. You could have 150+ crewmembers suddenly trying to get from their quarters to to their duty stations. You have a few elevators or stairways, that will easily lead to logjams. There are numberous turbolifts that use the same system, so a single access point could enable up to six cars or more to be accessed in quick succession, without having thirty crewmen twiddling their thumbs waiting for the car to drop off it's passengers on it's several stops down the ship before coming back up to take the next batch.