It was a good year for me and my wife. We used 300+ PPs across our accounts. 80% were transcons, 20% were TATL. Every PP upgrade was into a true Polaris seat. The easiest upgrades were on transcon 77Es as there were always 5-15 empty Polaris seats at T-24.
We had tremendous flexibility on when to fly so that helped a lot. UA's no-change-fee policy also helped as we could easily change flights when UA moved around their 'upgrade-friendly' large aircraft.
I think the '22 upgrade sweet-spot will be TPAC starting in the 2nd half of the year. I feel TATL PP usage will be tough as there are a lot of PPs chasing relatively few seats in 2022.