I am looking at UA flights within the US as part of a larger trip. I notice that there were significant changes to the options a few weeks ago, which seem to have been reflected a bit earlier in this thread. If I book now for early March, is that soon enough that the schedules are likely to stay about the same, or is there a risk of further significant change within the last couple of months? I understand there could be irregular ops on the day, but ideally I don't want to pay a bit extra for a hub-to-hub flight on a 787 and then get changed in advance to an A320 or 737 with possibly less convenient timing.