It is very inconsistent. Since the introduction of the new e-mails, I have gotten them consistently if I book the reservation myself an an agent never touches it. I have done several CFC's and I have gotten the e-mail notification though. But, if I book through an agent on a credit or voucher or something like that, I am never notified. I was, however, not notified at T-100 when my ORD/SEA upgrade cleared for my upcoming flight on Wednesday. Hard to say at this point, so checking the web site or using the mobile app to periodically check your seat is a good idea, particularly around the upgrade windows.