It also avoids wasting time (and write endurance) shuffling around data which is just going to be overwritten anyway. That could happen either as a result of st

It also avoids wasting time (and write endurance) shuffling around data which is just going to be overwritten anyway. That could happen either as a result of static wear leveling or just because the drive needed to erase a block with a mix of valid and overwritten pages to make room for new data.