schedule change?
Cow, I do this often. The strategy (IMO) is obvious..............
Wait until UA makes a schedule change (every few weeks). UA does not apply the same ridiculous rule as AC (+/- 2 hours = "significant"). Don't wait for a message. Log on and look for the red ink. Then call the 1K desk and say the sched change makes the flight no longer convenient. (I don't go into any more detail, as this can be so subjective.)
In the past 6 weeks, I cancelled w/o penalty:
xxx-EWR-SFO-TPE
xxx-ORD-LAX-PVG
The last one was more difficult. Two calls, two schedule changes and one e-mail. But it is done.