from the Samsung white paper, assumes that the RAID controller waits only 8 seconds (or 7 for CCTL) before it marks the drive as bad, enters degraded (or "parity") mode and flags that a drive needs replacing. In reality, this isn't the case for NASes, most of which use software RAID.
The responses I received from Synology, QNAP, NETGEAR and Buffalo all indicated that their NAS RAID controllers don't depend on or even listen to TLER, CCTL, ERC or any other similar error recovery signal from their drives. Instead, their software RAID controllers have their own criteria for drive timeouts, retries and when a drive is finally marked bad.
These software RAID controllers are generally more patient and wait significantly longer for drive response and execute more retries before finally giving up and marking a drive dead. While this may degrade performance slightly when dealing with drives with bad blocks, it's intended to reduce the occurrances of drives dropping out of RAID volumes and the subsequent long, risky rebuilds.