I'm getting screwed over by the absent ability to cancel an online check-in. I'd like to be able to utilize same-day confirmed changes on united.com as my flight time approaches, but I'm unable to do so once I conduct online check-in, which I often do at about 24 hours before flight time.

Is anyone changing their travel habits in favor of checking in online only just before their flight, so as to not compromise their chances to expeditiously process a same-day confirmed change?