3 employees of Google analyzed and summarized the behavior of more than 100,000 hard disks within their park. The study lasted nearly 5 years, from 2001 to 2006. The discs have a capacity from 80 to 400 Gb, assembled in parallel or serial, running from 5400 to 7200 RPM.

We learned, among others things, that there is no correlation between failure and a frequent use or a too high temperature.

The intensive use is an influential factor only during the first 6 months or after 5 years, whiwh is the average longevity of a hard disk. Oddly, a lower temperature can lead to a breakdown. Or of course a torrid heat...If a disc is in trouble, there is more chance that it will die sooner.

Source: Failure trends in a large disk drive population, last month.
For those who do not know: Revolutions per minute (abbreviated rpm, RPM, r/min, or r·min−1) is a unit of frequency, commonly used to measure rotational speed, in particular in the case of rotation around a fixed axis. It represents the number of full rotations something makes in one minute. The International System of Units (SI) unit for rotational velocity is the radian per second (rad·s−1).