I think the 'production' years come down more to preference in Pick-ups. As far as I am concerned, PRS don't seem to settle on what they have made and look to continuously tweak and evolve the instrument - but of course you also have the fact that guitars rely on 'natural' materials so you may want 'Brazilian' rosewood over an Indian Rosewood fretboard. I really don't believe that PRS have a 'bad' era - not like Fender's CBS era or the Norland era for Gibson either and have always made high quality instruments - therefore you may prefer an 'era' that used the 57/08 or maybe the HFS/Vintage over the 85/15's.
I would be interested to hear why they favour certain years - if not for the pick-ups that they were sold with as stock. I haven't got a Custom 22 myself - although my PRS Special Semi-Hollow is based on that. It has the 58/15's though (as well as a 57/08 NF) which are different to the regular Custom 22's 85/15's. I like the 85/15's in my Custom 24.
If you are buying a new '2020' Core Custom 22, you will get the 85/15's that have had the TCI process applied and of course, PRS's Nitro finish - so again its an 'evolution' on from the 2019 (and earlier) models. Those updates may well make people feel the new 2020 'era' is the 'best' because 'Nitro' as standard is their preference or the 85/15's with the TCI process are their favourites.