The older section of Corridor H only passes near two towns, Weston and Buckhannon. At Weston, the I-79 exit is a couple of miles out of downtown, but plenty of businesses have sprung up near the exit (there are at least three hotels, a Walmart, a strip mall, a Sheetz and at least one other convenience store, which I think is a BFS, and there are various fast-food places near the interchange and along the route into downtown. There's been some growth near the corridor at Buckhannon (a Walmart and some outlying stores, a newer Sheetz, a couple of hotels, a Dollar Tree, and a Lowe's) as the four-lane passes very near the downtown area. The corridor really doesn't come that close to Elkins, and all of the major development is on the south side of town.
Beyond that, along the newer sections, the route really doesn't pass near any towns to provide them a boost. There's been some growth at the exit at Moorefield (a Sheetz, a McDonald's, and a few other places) but the road won't really come all that close to Parsons or Wardensville. Thomas and Davis seem to be propped up by ski areas and Blackwater Falls visitors, so it's doubtful those two small towns will get a boom.
Along Corridor L, it's fairly built up between Beckley and Fayetteville, but Summersville is the only other place along the route that has significant commerce, and a lot of that is probably tourism-based as well.
Corridor D is desolate (although there's been a few surprising businesses pop up at the Harrisville/Ellenboro exit) and Corridor Q serves two towns (Princeton and Bluefield) that were already well-established.