Ultimately the hard drive will need to feed the ram or pull from the ram so there will be a time limit to how long ram buffering will work. This could really create a problem with a high track count recording where it starts off working well and then runs out of ram because the drive has reached its limit. The recording that you thought was working suddenly isn’t.
I remember the days of testing hard drives where measurements were always on my radar. It has essentially become a non issue for me now.
Dean