Sounds like you're expressing a personal, unfounded opinion rather than actual facts. If you've got something other than your say-so to substantiate this claim I'd be interested in reading it.
Sure thing; how about this:
https://groups.google.com/forum/mes....pc.hardware.storage/9CvsLZo5V38/ugOXpHD7sN0J
Those are comments from someone who worked directly with hard drive manufacturing.
He points out that while there were benefits to using it on MFM/RLL drives, those were incidental; also, he states that nearly all claims Spinrite made for IDE drives are invalid because you can't LLF IDE drives.
You sound like you believe that SpinRite can be run on a raw, unformatted drive, which it cant! SpinRite *only* runs on valid partitions that can be accessed by DOS. If you've used SpinRite you should be familiar with that feature.
I was making no such claim, only stating what a proper MFM-from-scratch workflow should be. If your drive has an attached defect list, you've got to LLF and enter those in, or those sectors will come back to haunt you someday regardless of what Spinrite says. (Spinrite 6.0 works with unformatted drives, btw. But, Spinrite 6.0 only works with IDE drives and drops support for all others.)
I purchased Spinrite II and upgraded to 5.0, both in the 1990s. I grew disillusioned with the program but still pre-ordered 6.0 in hopes that the complete re-write would offer some additional features that you really need for drive recovery, such as the ability to restore damaged files to a
different device. What we got instead was larger IDE support and a SMART display (which is a display only, there is no indication it is used for anything other than notifying the user that their drive has surpassed a SMART threshold). It is precisely because I have used it so much over the years that I speak against it.
Spinrite is good for quickly determining what the optimal interleave is for a particular system+controller+drive combination, and I still use it for that. But after that determination, I always LLF the drive using the controller's built-in facility. And there's no point to using Spinrite on IDE drives for any reason because it can't actually do anything to fix them.