Nit: if you count harmonics, you only need 14 frets to play high E on every string in standard tuning.

Harmonics should be denoted differently. For such notes, you can only play the same note on at most 3 different strings.

I wasn’t responding to the broader topic about music notation, only picking the nit on the claims about whether you can play the same note in six positions on a standard guitar in standard tuning. If you count harmonics— acknowledging one may not count them—but now I’ve repeated almost my entire comment.

If you have an ear then a harmonics should not be counted as the same note. To a layman, they probably can’t tell the difference between the same note from a different string. But it will be very obvious to even a layman a harmonics has a different quality.

That’s the reason they have a different notation. The notation is there to convey what we mean, not a nitpicking. To claim it is still the “same” even when the notation isn’t are really pushing what “the same” is. We might as well start to count the way one scratch on the string to be the same note if they gives the same fundamental.

My pedantry and your pedantry are totally orthogonal. You are, of course, correct in the pedantic points you’re making; the pedantic point I was making, however, was not intended to dispute or even discuss these points.

I could bring the points closer together, say by pointing out that fretted notes also exhibit harmonics; or that picking technique and position can significantly enhance or mask that fact. In so doing, there would certainly be much to dispute if I suggested without any qualification that any pronounced harmonic intonation is “the same” as any other intonation lacking the same pronounced harmonics.

But all of that is moot. I didn’t suggest any of those things. And I did include a qualification that invites you or anyone else to count or not count harmonics as you see fit!

You could just say “I don’t count harmonics”, and I would have no quarrel with that. But I do object to repeatedly conflating my point with points I both did not make and already clarified I did not make, to dispute something I am clearly not saying or even discussing.

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

Again, all of what you say checks out, but none is responsive to what I said. I appreciate your dedication to accuracy and I’ll leave it at that.

I suppose a lot depends on what we mean by standard. For example the number of frets varies. Classical guitars are usually 19, acoustics are typically up to 20, and electrics 21 or 22 but sometimes 24.

Those with 24 frets can play E4 on all six strings, but 24 frets is pretty uncommon so I can see an argument for calling those non-standard.

But how about a 22 fret electric with a whammy bar? Those are very common. The highest note on the 6th string without using the whammy bar would be D4. Can you pull on the whammy bar enough to raise that to E4?

The comment I replied to mention sheet notation, last I check we only use that with classical guitar.

(But even “classically”, there are other guitars with many more strings or other tuning systems, etc.)

Lastly, “standard” can be perceived as the most common guitar you can think of. It is very likely if you tell a random Joe go buy a guitar for their nephew, it will be 6 strings 19 frets with EADGBE tuning.