My ride from home to the train station is just under 1 mile and I bike that on days that I take the bike. It is a very walkable distance but who wants to carry a folding bike that far? On the other end it is 4.5 miles from the station to work. You could walk that too, it would just take a lot more time. If I had a 2 mile total commute I think I would bike it most of the time. If the walk were pleasant I might do that occasionally for variety.
Ken