This is all very interesting. I often specifically choose flights to have a daylong layover before heading off TATL. First flights of the day are the most reliable and I can work from the airport during the day without fear of missing connections.
These layovers are typically well over 4 hours, usually 8 or more. They have always been presented to me in search results on United.com without much prompting.

I haven't ever dug into fare rules, so not sure if I am just on exception routes or getting lucky somehow. Really hope I haven't jinxed it now!