Another thing to remember is some of the really older disks will have larger magnetic areas as platter density wasn't nearly as much. As densities increased the amount of total charge per bit decreased as there's just less magnetic material available. Just one of the many factors of how likely you are to experience any issues.

Refreshing every five years for magnetic storage is probably overly cautious to me from my own personal experiences. But FWIW if it's data I really care about it doesn't spend years sitting around on just magnetic media. For my own personal risk tolerance putting important data on say an external hard drive and sticking it on a shelf isn't a great way to archive data. I might do it with data I'm OK with eventually maybe losing, but if it's something I know I'll want in 20+ years it gets a few copies with one being on some highly reliable optical media like M-DISC.

Your hard drive might go a long, long time without losing a bit. And maybe if you do lose some data, it's a couple of typos in some help file. Maybe it's some rare code path in an executable that almost never gets called. Maybe it's some b-frame in a video that you'd never even notice. Maybe it's some important bits of the last photo you had of a loved one. Maybe it's some important field a database. Maybe it was empty space. Who knows.