those media issues are a real problem for all these burners which support is discontinued.
Although, these burners are so old (but so good in case of PX820 Parker knows what I mean), that burning in 8x, 12x or even 24x is way below normal CDR acceptance. So it shouldn't be a problem (also with some luck involved ).
I've got a PX8/20, PX12/10/32, PX24/10/40 (& some others ). I've no problem writting on any kind of media (some are 3 years old in their original package !). As a matter of fact, when I buy CDRs, I don't care choosing carefully. I take the first or the cheaper, and I never complained... I tested all kind of media I could grab (black, all flavor (color ), 74 min, 80 min, 90 min).
I must admit that's a bit lucky, because why not imagine that some brands or CDR are tuned for being burnt at high speeds and could misbehave in these old-slow--feeble-laser "burnbuddies".
The only backdraw I get these days is with CDRWs. There I suspect a firmware (discontinued ) could solve the problem. My 121032 can't sometimes even recognize some CDRWs, whereas 241040 have no problem, also my 241040 is dying (can't read some CDRW it just burnt, but PX40TS can ) -> time for replacement.
Facing the strange problems with CDRW, I made up some assumptions: first CDRWs last someday (obviously), second: the newer the burner is, the better the support for newest CDRW is (obvious too in fact).
I don't have a Litey (so can't use WSES), nor do I have a Premium drive (yet), so I can not do some extensive tests on suspicious media, and I'm stuck guessing what can be (CDRW related prob).
Hope it's not a poor hardware issue (CDR(W) drives decay too, this isn't a CDR(W) media monopole), as PX820 is really a good drive, a little bit vintage now (to be put in a museum if it didn't show so good behaviours with recent protections) .