Sorry; I failed to end my italics in the first paragraph of my previous post.

Anyway, I think I covered the matter of counting up to the fourth and fifth notes in a scale when I talked about the white keys of a piano (i.e. the C scale). I was counting the "I" as the first note of the scale, just as you did.

However, when I talked about simply counting frets up the guitar fingerboard, I did not count the starting place as one of the frets. In other words, in my example of counting up from C to F, the C (let's say the one at the 3rd fret on the 5th string) was counted as "number zero". In this example of the 5th string, the C is on the 3rd fret and the F is on the 8th fret. 8 - 3 = 5 .... which matches the count you made in your post of 9:19 PM.

So I think we're on the same page.