This NAS, a lenovo ix4-300d, came with Seagate drives (ST1000DM003), so its whatever the SMART 240 counter (Head flying hours) means to Seagate I guess. I just interpret it as "not parked", so it could be doing anything, but this NAS is not doing huge amounts of I/O - mostly just for music, movies, and some personal files. I think all the heads for all platters are on one assembly so they are either all parked or all spinning.
Is the 10y head flying for each head? Is it for heads actually reading/writing, or just for spinning drives/aloft heads?
I only skimmed the charts, they seemed to just measure time/years, but not necessarily drive use over time.