It is so RARE an occasion
to be able to disagree with BOTH of you
that I cannot miss it
You seem to forget how the "solution" is actually the solution to an original quite "narrow" problem, or actually is/was a cure for a single, specific "illness" that presents/presented with two specific symptoms (LBA0 and BSY).
At the beginning of this story, we knew for a fact that these Seagate disks had this "congenital" disease, that presented itself with these symptoms.
But the cure was intended for the illness, NOT for the symptoms (if provoked by another illness).
Let's take Aspirin as an example.
Aspirin is good for "common cold" and consequent fever.
Aspirin is also very good for "rheumatic fever".
BUT it is NOT a cure for *any* fever and actually doses to cure the two different kind of fevers above are VERY different AND the time needed to have a positive effect varies.
A patient having a "common cold" will be threated with Aspirin for (say) three days with relatively low dosage.
A patient having a "acute rheumatic fever" will be threated with Aspirin for one, two or more weeks with relatively high dosage.
If you prefer the same "cure" when applied to different illnesses will produce beneficial results in different times.
We know (or presume to know) that when we apply the "solution" to a disk that is in either BSY or LBA0 BECAUSE
of the original log position issue, the message comes out in a few seconds.
We also know that in some cases the time needed to get to that message is much longer.
This could well be because these latter disks (expecially if recent and not being affected by the congenital "factory + SD15" issue) have another illness, let's call it "rheumatic fever", that - by pure chance - has the same symptoms of "fever", BUT that is NOT caused by "common cold".
It is also well possible that the "optional power down" is not-so-optional when curing "common cold", but it is vital (or completely unneeded and possibly counter-productive) when curing "rheumatic fever"....