It shows the "on" time in hours, so it takes a little math to get the time in months or years. It is very useful in determining how much warranty one might have left ...
I think this is all moot, so let's simplify this a bit.
The hours operated do not matter, but rather a flat and very firm build date. Most are 3 years with 5 years for some newer or higher end drives. The rule of thumb is 3 years though, and that should
be on the label. They don't care how long it was actually used one bit.
My point is: If it's built in 8/07, it doesn't matter if it only ran for 5 minutes. If it's out of the printed warranty period, it's out. Doesn't even matter if it sat on the shelf for 3 years and you just got it yesterday...it's out of warranty if it had a 3 year stated period. The thing is, they'll probably say "no" even if you show them any other proof that it never turned a spindle once. I mean, I have an old Quantum Fireball that might have ran 7 months, always on, and there's no way I could ever get it replaced.
Warranties are black and white with no gray. They're based upon the day they released it from their factory and into circulation. To even start a warranty process, you enter the Model# and SN#, it's in their data base, and you proceed from their info or you don't.