These timing bits were necessary on the disks for the reading head to be able to tell 1's from 0's, but copiers did not have the ability to maintain them, so copies were often desynchronized.
AppleSauce is the only device that can successfully preserve timing bits, hence allowing protected disks to be copied.
Source: I crack Apple ][ programs for fun.
The more important part about spiral writing was that it defeated the track-by-track copy of most Apple ][ copy programs, since there was no disk position synchronization available on the consumer drives. Note that the Applesauce device modifies the drive to allow for this.
It was more a matter of which bit copy software had the right profile to be able to copy the tracks.
Back when I was doing a lot of copying disks, I remember it was really important to get the drive speeds right for a given profile. That way the you could dead reconing style copy for a partial track once the drive sync'ed to some known pattern that was fully on the starting track. These copies obviously didn't work 100% of the time, but generally a few tries would yield a working copy.
I personally used Copy][ Plus as my primary utility and vaguely remember writing little "scripts" (more a few bytes of hex codes IIRC that described which tracks to read, and how to do quarter stepping/etc) to describe how to copy spiral track disks. Although frequently, I remember it being easier to try one of a number of other bit copy utilities first.
Uhh, mind elaborating on this?
Basically, they created a disk that could accept writes everywhere except a certain sector, something you could not replicate with even a perfect copy.
It was a bit silly to be honest -- this was the easiest copy protection to bypass!
The protection is not the hole in the sleeve, it's the hole in the disk. For example, the garbage reads would happen on track 12, $230 bytes after the $D5 $AA $96 marker. Good luck physically reproducing this.
These protections are trivial to remove in code, though.
And having made multiple copies like that, I know very well it worked pretty well as a method -- it's very likely why that method never became the 'uncopiable' it was claimed to be when it came out.
That is of course why its not just a simple case of locating where the burned hole was relative to the sync hole because the "physical" location of a sector offset on the disk would normally vary from disk to disk (or for that matter from track to track) or format to reformat.
High end commercial copiers really didn't come into play until 1984-5.