It is not about counting harmonics or not, but what should be counted "the same". We could have gone all formal here, musical theory and physics and all that.

It is not about counting harmonics or not, but what should be counted "the same". We could have gone all formal here, musical theory and physics and all that. But I claimed that you can just tell by ears and use common sense. What I was going for is accuracy. Someone made a quick comment that one could have played "the same note" on all 6 different strings, which aren't correct under closer inspection and reasonable assumption to define the context. Similarly, if you include harmonics in the definition of "note" (while still hold the distinction that harmonics are different from normal notes), then still you cannot play "the same note" on all 6 strings, and in fact even lesser (for the same harmonics to be played on different strings) due to the constraints. Interestingly, if you also include artificial harmonics, (again, while still hold the distinction between normal notes, harmonics, and artificial harmonics), then yes, you finally will be able to play the same note on all 6 strings, theoretically. One could argue whether we should consider harmonics and artificial harmonics the same, as they share different notations, and requires different techniques, but sounds the same to the ear. But either way there exists artificial harmonics that you can play on all 6 strings. QED