Acronis Drive Monitor - Power on time
Apparently our client's disk has been use over 59 years!
21657 days, to be precise. It's given a health score of 94%, not bad for a disk of that age.
Perhaps your formula for giving an intelligible indicator of disk 'mileage' needs looking at?
Perhaps the Guinness Book of Records will be interested in this drive? :)
I don't think Acronis actively support or develop this utility anymore so any 'oopsies'' are likely to stay there.