Time Limited Error Recovery is a drive feature. When enabled, the drive is supposed to not try very hard to self-correct media errors, so that it is guaranteed to always either succeed or fail within a known, short, time interval. This is useful for RAID1 arrays, where data is replicated (mirrored) in other places (and also for other mirroring RAID types).

But it's a bad feature when the drive is the only drive with the data --> for this, one normally wants the drive to try really hard to recover the data, even if it takes 10-20 seconds to do so.

For some peculiar reason, WD is treating this as a permanently enabled/disabled feature, dependent upon different firmware versions. Rather than just having the feature present in all firmware, disabled until the operating system sends a command to enable it.

Weird, but that's how they do it.