>the country is long and narrow
This is a little counterintuitive but it does make a difference.
I recently moved from a coastal city (that is very linear) to a landlocked city spread evenly in all directions. I had naively assumed the new city would be easier to get around in, since on average places would be closer to you. But the first city has decent commuter rail, which meant I could get to the other end of the city in an hour, and use cabs for last mile connectivity.
I'm sure you can have good public transit in "round" cities too, but it is certainly more difficult to plan.
>I'm sure you can have good public transit in "round" cities too, but it is certainly more difficult to plan.
You don't have to be "sure", take a look at London which is a "round" city with excellent public transit.
Round cities are even better for rail. You run a line in a circle, like the Yamanote line in Tokyo, and now it has the advantage of periodic boundary conditions. Everywhere is central!