One common complaint I've read on the forum is that there are not enough rest areas available in some states and that rest areas that used to be available have since closed down or are otherwise unavailable. I'd like to turn that question on its head: are there any states or provinces that have exactly the right number of rest areas, and are there any states or provinces that have too many rest areas and would benefit from closing them down?
There is never too many rest areas. There is such a thing though as supporting a budget for too many rest areas. Arizona ran into an issue several years ago where they closed several rest areas to save on funding.
MN does a decent job with its spacing and amount of rest areas I think, including the occasional non-interstate rest area.