When you spin up the drive, the motor has to overcome the mass of the disks to bring them up to speed, requiring more torque, current, and wear, than just keeping them at that speed. On the other hand, bearings don’t wear out at zero RPM. Bearings go, motor goes, either way drive is dead. Regarding bearings ALWAYS mount drives so that they are horizontal, this results in minimal bearing wear and load.
@MangoPenguin Same thing that happens to your car motor when you slam the accelerator from a dead stop rather than gradually accelerating and maintaining a steady speed. Everyone knows stop-and-go traffic is hard on cars, disk drives too.