(St Mary's could also be in the running but already has several Boston Hubway stops nearby).
Thats a good thing.
Say you spread your stations out, 1 mile or more apart. And then say you arrive at your destination and all the docks are full. Now what? Riding a mile away to dock defeats the whole purpose of using the bikes...and it leaves a very sour note.
If youre at one station, and you can actually see another one from where youre standing, thats almost never a problem.