Accidental options explained

Can anyone explain the purpose of the “first occurrence” accidental option?

I’m a little unclear about what it does and why it’s there. I had thought that it only affected the first note of the next bar (as seems indicated by the pictures), which I would find useful, but as the text below it says, it seems to completely over-ride the preceding options for both octaves and unisons.

It says that other accidentals later in the bar will be suppressed if that option is checked; but there are also other options for whether successive accidentals are shown in the same bar. (Accidental duration rule; Notes for which accidentals have already been stated)

I call this the “Holab option” since it was requested by experienced engraver and publisher Bill Holab, who has worked for many of the top publishers in the US. For him, the most important thing is to ensure that the first occurrence of the note in the following bar definitely gets an accidental, regardless of whether it’s in the same octave. Bill is an engraver whose opinion I trust (though I do not always agree with him) and he provides some perspective on how conventions differ in the US.

But isn’t that exactly what a cautionary does in any case? If you’ve set the previous two option to show accidentals in the next bar, that will always apply to the first note at that pitch in the next bar. I still don’t see what extra this gives.

Personally, I’m more likely to want a cautionary on the first note of a new bar than further along.