Yea, that's what the manufactures claim. I'd put it up there with "The check is in the mail" and "Of course, I'll respect you in the morning" in the list of Great Lies of Modern Civilization. 

I've painfully found that unrecorded CD's last no more than five years, and then I cannot write them. I have some CD's of backed up software from 25 years ago which I can no longer read correctly - they have significant data loss, which causes the drive to return errors when trying to read the data. The source code I backed up onto those CD's is now relying on whether I can read some 4mm DAT tapes, and if I cannot read those, then all that work from back then is gone.

Much of the longevity of plastic CD/DVD media is in how it is stored. If it is stored in excessively hot conditions, or stored in the light, or in humid conditions, I find that it can degrade in as little as five years. My media has been through three moves, highly variable conditions, and not a lot of care. I'd say that my case has been a pretty good torture test for digital media.

Back in the late 80's, before rewritable CD's were available on PC's, I did a consulting job for a company writing software to enable a Macintosh with SCSI interface to use their optical storage drive. At the time, I was able to talk to their hardware engineers and we got into a really productive discussion over sushi and beer about plastic vs. glass discs for backup and distribution formats. The glass discs were, as you'd expect, fragile, but the Phillips engineers said that glass was vastly better in durability of data than plastic, and their testing for plastic discs showed, even then at much lower densities, that the data lifetime might be limited to 5 years in average user conditions (eg, write a disc and toss it into a desk drawer), and up to 10, maybe more, in "ideal conditions" which were temp/humidity controlled, someone who knew to never touch the coating of the disk, someone who operated their drive in a low-dust environment, etc. The glass discs went nowhere, because they cost (back then) about $50 per blank disc.

Given the really uneven results I've found this winter in trying to recover some CD's from three moves and 25 years ago, I'm looking into the new magtape formats for backup called "Linear Tape Open," which allows one to back up 1.5 to 3 TB per tape cartridge. I've found that tape formats are more reliable than disc data storage, in general.

I'd say from experience with rewritable CD's that you can depend on maybe 10 years, if you're careful. More than that, and you're rolling dice. I rolled the dice in my vast collection of media and sometimes I'm coming up with snake eyes.

Mind you, I still have 800, 1600 and 6250 bpi 9-track mag tapes, DEC TK-50 cartridges (try to find a way to read those anywhere), 3.5 and 8 inch floppy discs (probably all worthless by now), 8mm tapes, 4mm DAT's, CD's, DVD's, and who knows what else. My wife often asks me "Why do you keep carting all that crap around? You haven't tried to read any of it in decades. Dump it." Well, this winter I listened to her, and she's correct - I can't read it, and a bunch of this stuff is headed for the dump.