In case this interests or reassures anyone, I'll report the following.
In the 1970s I did a large amount of documentary sound recording onto Dolby B cassettes. In the 1990s I bought a second-generation Philips 2x SCSI-based external recorder, about the size of the main unit of a standard desktop computer, and started transferring those cassette recordings to digital. Blank CD-Rs at that time typically sold for around $25 apiece. In some cases I also made data CDs containing the .wav files, but it was quite time-consuming and expensive to make additional discs. Years later when DVD-R drives became available, I started copying the contents of those CDs to DVD-Rs. I used Plextor (SCSI-based) CD drives to extract bit-accurate .wav files from the audio discs. But I still kept all the CDs, since I was afraid of losing any recorded content.
For many years these discs sat on my shelves. In the past few days I've started transferring all this material to a portable SSD. I can report that the materials have held up VERY well. Very nearly all the old discs have been completely readable. I've made binary file comparisons between ALL the source CDs and the DVDs that I copied from them 20 years ago; absolutely all the data has verified 100%. I'm talking about 1000+ CDs and hundreds of DVDs--almost 2 TB of data so far.
Worst case, the Pioneer Blu-Ray drive that I'm using to read these discs has had to slow down occasionally to read some data (evidently retries are occurring at some low level). I've found that in most cases, if I carefully wipe the disc surface with a cloth, the same disc can then be read without the slowing down. Also, in such cases, before/after comparisons have shown that if a file on a data CD or DVD can be read successfully at all, the binary data that's received is the same, no matter how much extra work the drive had to go through in the process. (I always clear the PC's memory cache by putting a different disc into the drive in between the trials; the discs were definitely being re-read physically in these comparisons.)
In the intervening years I had made other, previous attempts to extract digital audio from some of the audio CDs, and had encountered read errors on a handful of them. These errors, however, mostly cleared up on later attempts when a different DVD or BD-R drive was used. The drive that you use really matters to a considerable extent, particularly with digital audio extraction.
The very few mishaps (maybe two so far) were recorded CD-Rs that appeared completely blank to the drive. But still, that's a separate case from bad data from a disc that could be read, which I still haven't seen.
--best regards
P.S.: During this project it occurred to me that I might wear out my BD-R drive, and I started looking around for a backup. The model that I have (Pioneer BDR-208D) is no longer made, and most of what I'm seeing on the market now is "slim-line" portable stuff that isn't as fast or solid. Probably that stuff is being made for people trapped in the Apple universe, where optical drives are now available only as external USB devices, and there's a premium on the drive being USB-powered.
I eventually found an updated Pioneer model that looks like a good potential replacement; I'll buy one just in case. A few Plextor drives still exist in the universe as well (which do a better job with CD-Rs and DVD-Rs than anything else I know of). But this is maybe something to think about--for those of us who have large collections of material on CD-Rs and DVD-Rs, what would you do if your current player crapped out? I'm concerned that in a few more years of this price- and volume-driven market, there may be nothing but slower, less reliable drives available for reading those discs.