Well it is mostly flat! and most of my shifting use is for starting/accelerating vs. straight line riding... and for the occasional climb of a bridge or other minor climbs which hardly ever get me more than 21T on the rear.

So I agree with you that it makes sense I don't use that many gears, but since the terrain is easy, I should be able to use the faster gears more often, and not only when touring and I know there is 2 miles of downhill ahead of me...