Is the Zip drive really just a big floppy drive? My understanding is that the Zip drive was a tech spin off from Iomega's earlier Bernoulli Box. Unlike a floppy disk, the drive head in a Bernoulli/Zip drive is not in constant contact with the disk media. The rotation of the disk generates a "wedge" of air that lifts the disk head away from the media. During active use, the disk head does not touch the disk media; the head only touches the disk when the disk is "parked" or "spun down" or starting up.
Thus we can conclude that constant rotation of a Zip drive is normal behaviour. If the disk stops spinning, the disk head must come in physical contact with the disk; either in a "parking region" or a random part of the disk, close to the last read/write. When a disk is "spun down", the head is touching the physical disk, so wear to that disk region is inevitable. [Hard disks use mechanical rather than aerodynamic systems to separate the disk head and media; they can automatically "park" anywhere; exceptions include early Mac drives that provide "disk parking" utilities.]
How does that affect vintage Mac users? Unfortunately, we don't know the algorithm that the Zip drive uses to determine whether to park or not. Is it just 15 minutes of non-use or something else? If I shut down more frequently, will I suffer from disk wear?