Last summer (2015), I was told by multiple call center agents that UA had officially ended the practice of "protecting" fliers. That is, they would no longer allow you to simultaneously have seats on two or more flights from A to B, where extra seats are booked in case of a misconnect. The rationale was that it was causing problems because fliers never cancel the protected seats when they make their original flight. Why UA's software can't automatically detect that the later booking is not needed, I don't know. But that was the rationale that I was told.
That said, on multiple occasions I was able to get myself protected by simply hanging up and talking to another agent.
Since last summer, I've actually never had occasion to ask for protection on a flight, so I don't know if call center agents are still hesitant to protect fliers.
As we all know, there is not really a canonical set of UA rules, especially regarding how to handle passengers during IRROPS. In a complicated scenario, five agents will tell you five different things. If you want to be protected on a later flight, just hang up and call again if you don't like what the first agent tells you.
But if you manage to protect yourself on multiple flights, be a good citizen and call to release your seats once you know you won't be needing them. What goes around, comes around!
