: I also see them on the late manual Autavia with Tach bezel and red stopper.

That's the key right there Ron. We see them on the late 60s manual output and crossing over into the early Chronomatic watches (and manuals in the equivalent case). On the first gen Carreras, for instance, we should only see them on second execution examples (the ones that also have inserts in the markers); anything earlier and the hands have been replaced at some point.

They're particularly nice in gold, I reckon: