Comment by userbinator

I think you're talking about two different things; "adaptives" are usually stored in EEPROM or the MCU's NOR flash, which is basically better-than-SLC levels of reliability, especially as they're written once and treated as ROM after that.

OptiNAND is a "SSHD" and thus has the same concerns with retention as an SSD. https://en.wikipedia.org/wiki/Hybrid_drive