NOTATIO

I am a bit at a loss here.
I had always thought that the tremolo slashes for the timpani roll (that is a repeated, unmeasured tremolo on the same kettle) were the old notation and that the new, most accepted notation was the one using trill sign and wavy line extensions.
Now, looking at Gould—which so (too) many are taking as a holy scripture—it seems that it is the other way around.

Could someone clarify this for me please? Possibly a timpanist, of course.
Thank you!

I think Gould is right. I've used both notations without comment from the timpanist (I am not a timpanist myself), so I don't think it matters very much which you use.

the trill is the "old notation, yes.
logically speaking, you cannot "trill" on a single timpani head.
so the consensus is that a slash tremolo notation is more accurate and correctly represents what is being performed on the instrument.

Perfect, then!
I will stop being a boomer