Normally the maximum domestic connection time allowed is 4 hours. At the same time, UA will allow you to stand by for earlier flights.

Thus, has anyone booked a 4 hour flight connection for say, the afternoon, but stood by for an early morning flight as a means of obtaining a longer connection between flights (i.e. 8 hours)?

The idea is to get a FREE stopover of 8 our in a hub such as ORD or DEN.

If one were to stand by and take the earlier morning flight, would UA then force you to take the corresponding earlier connection to your destination, or could you still take the previously booked evening connecting flight (thereby garnering an 8 hour domestic "connection")? Or would they charge you extra for taking an evening connecting flight which was past the 4 hour window?