Thanks for the replies. To summarize, I think people are saying the reason my DW1655 fails burning YUDEN000T02 media at 4x after a handful of burns is because it turned off Solid Burn after it fully learned this media, and because my media may not be a good batch and/or I shouldn't burn below the rated (8x) speed this caused failures on every subsequent YUDEN burn (until I turned SB always on)?
While I realize that my 8x media is more likely optimized for 8x, if my batch of media is bad then why do I get great burns (typically a 97 score with only a few PIF spikes between 2 and 5) at 4x when Solid Burn is on? I thought by definition you can't get very good burns on poor quality media even with SB on. I've tried 8x burns on this same media batch in the past on other drives and the 4x vs. 8x quality scans are about the same. If SB turned on can produce beautiful quality scans on any type of media, including a bad batch, then is there really such a thing as bad media any more?
My reason for burning at 4x is this: there are lots of spots and scratches near the edge (thanks to the Fuji spindles these came on). I found when there is a bad spot, the PIF mountain looks worse at 8x burn than at 4x, so I was hoping 4x burning would have less of a problem with the spots near the edge.
So, I should try clearing the EEPROM in QSuite to erase my 4x learned media and burn all my 8x media at 8x. Then once it re-learns the YUDEN media at 8x, I could let it turn off Solid Burn and theoretically it should do a better burn job than Solid Burn and it won't ruin every YUDEN disc like it did at 4x with Solid Burn off? If this is correct, I think the drive's behavior is strange. You'd think the drive would be able to detect when a learned strategy is doing a bad job and revert to Solid Burn on rather than trashing the media. This undocumented "feature" caused me to return my first 1655 as defective when it wasn't. I guess the reason nobody else encountered it is I must be the only person who still burns mostly at 4x.
It sounds like the drive always keeps learning, so if you burn at 8x for a long time and switch to 4x briefly, the 8x learned results could be tainted. I don't know if the drive uses a weighted average for its media learning. It sounds to me like the best strategy is to leave SB always on. If it only adds 1 minute to each disc, I can live with that.
I found a few other threads discussing SB and WOPC, but there doesn't seem to be a FAQ discussing them. I'll read those threads to see if I can understand all of this.