About 2 years ago, the system reported maybe 50% of my upgrades. Now, or at least over the past year, it's 100%. Woo hoo UA!!

I have noticed that if you're waitlisted for an upgrade that doesn't involve 500 milers and the 100, 72, 48 hour windows (i.e. WL on an int'l flight using a SWU)...you won't get a SMS. For that, you need to check My Itineraries everyday.