Not a micro-haul but in the spirit of the original post...

In the mid-late 90's, TWA used to fly once a day each way between two non-hubs: DFW-MSY (10am) and MSY-DFW (10pm). My understanding was that they were repositioning a plane used for JFK-MSY and then DFW-STL.

I always called that flight the Jazzfest special. In a market dominated by AA and WN, the MSY-DFW flight was the only one that left late enough in the evening to allow a full day at Fest; plus the DFW-MSY was timed perfectly to get you to Fest around noon.