The fascinating thing about these issues is their widespread inconsistency, affecting all manufacturers across a wide sampling of games over a long period of time. It almost seems random.
But the most frustrating thing is, it's happening on playfields made by "the professionals", right?
To wit, over my 5 years in the hobby I've restored a few basket cases, learning and trying new methods as I go. My first pin was a Space Shuttle that I partially (hand) repainted then cleared with Varathane 5 years ago. My next was a destroyed Firepower where I had to replace nearly all the inserts (even had to route the arrow holes biger since the new ones would not fit for some reason) and I used Spraymax 2PAC for that. My Bad Cats was a full hand-repaint and DiamondFinish Clear. And I just finished a barn-find rat's nest El Dorado with the DFC again.
I'll never say any of those games will pass the full "NIB / tightass collector sniff test" - my foibles, mistakes, and learning tells are still there; OTOH whatever defects there are, I know *exactly* what I did wrong to cause. AND YET, I've taken the first three games to shows, each has well over 1000 plays, some over 2,000.... And they are flat, smooth, and mostly wear-defect free. My Firepower inserts haven't popped or ghosted. I *don't* have any post rippling. Dimples? NONE! No clear chipping, planking, or abnormal wear with the sole exception of the impact zone from Space Shuttle's ramp air drop, as you might expect after thousands of plays over *years*.
Unlike Stern, JJP, Spooky, CPR, et al I'm just a newbie idiot learning as he goes, doing this stuff in suboptimal conditions with amateur equipment - yet my results seem to be pretty damn durable. So just WTF is going on in the professional realm? It has to be rushed schedules... that's the only thing in my favor, just plodding along letting things cure as I take my time. But even then, the "cure" was generally only a few weeks as opposed to months - surely any manufacturer could do the same.
The other thing is my older games were obviously well seasoned with older settled wood and legacy playfield inks. But my restores have all been acrylic paints and homemade decals with no apparent issues with the various clears I used. You'd expect the pro manufacturers to use better stuff and/or know what they're doing, so again, what gives?
Kinda sad when a newbie experimenter idiot can make a more durable result for a couple hundred bucks, than pros charging $6-7-8-9-10+K for NIB...