I'm adding a room in a basement and running a couple of new circuits.
Since the electrical boxes are a trivial expense compared to everything
else, I have purchased the largest capacity boxes to use for all my
outlet and switch connections, rather than buying smaller capacity
boxes where I have only a couple of connections to save a dime.

I have assumed it is against code to have a box that is too small, but
fine to have one that is larger than required. Is this in fact the
case?