Speaking as someone who’s done disk drive firmware for the past twenty years, you got me curious. There have been so many tricks like this, it would probably boggle your mind.
It looks like pre-caching was the one you were aiming for but that’s been implemented many, many times, especially in streaming applications. Heck, I’ve implemented it myself 20 years ago.
Is the second thing you’re asking about PRML (Partial Response, Most Likely)? Basically, the signals from the platter are coming in so fast there’s no time for the wires to form a nice clean signal so we take our best guess at whether it’s a zero or a one and then let error correction fix it.