Question by Damian Martell
The guitar fretboard has 2 E strings on the low E you label go's E F# F G ,but on the A string it Go's A B flat B C Why are some flats and some sharps? Couldn't the E string go E E flat and the A string A A#.
There are times when it is correct to use A# instead of Bb. When looking at the natural order of notes, however, the two are interchangeable (enharmonic), depending on whether you're ascending (sharp) or descending (flat). I've merely picked the sharps and flats most commonly referred to in that general context (i.e. when we're not moving up or down in half steps).
It is only when identifying a given key signature in which chords and scales are used, that we need to be more specific about labelling notes sharp or flat, to make the notation easier to read.
For example, if we were in the key of A, we would rarely use Ab along side it, because that would mean the presence of two As. When spelling a scale out, you pick sharps or flats for consistency.
E flat scale...
Eb F G Ab Bb C D Eb
C sharp scale...
C# D# E# F# G# A# B# C#
Personally, I just like to keep the note names consistent (I cheat in other words). Bb will always be Bb to me. But this is more down to how I visualise the function of notes. I don't like to overcomplicate things and doing things this way has never hindered my understanding. I rarely feel the need to write out a scale's notes, rather just know the key and its relative intervals.
Take a look at this link for more info.