Hi, basically you're right, keys with that many accidentals are avoided...
If you look at the 'sharp keys' in increasing number of sharps (from 1 to 7), we have:
- G (1), D (2), A (3), E (4), B (5), F# (6), C# (7)
If you look at the 'flat keys' in increasing number of flats (from 1 to 7), we have:
- F (1), Bb (2), Eb (3), Ab (4), Db (5), Gb (6), Cb (7)
So, if you look at the keys with 7 accidentals (C# and Cb)...
- the key of C# (with 7 sharps) has the same notes as Db (5 flats), so Db is generally preferred
- the key of Cb (with 7 flats) has the same notes as B (5 sharps), so B is generally preferred
The keys of F# (6 sharps) and Gb (6 flats) have the same number of accidentals, and both contain annoying notes (E# and Cb respectively), so neither is really preferred, they both suck equally!
So, all the keys can be used, but for those with 7 accidentals (C# and Cb), enharmonic keys with fewer accidentals are used if possible.
Anyway, I would argue that this only really affects people reading standard notation, so for most guitarists it's not something to worry about. The circle of 5ths/4ths can be useful in practicing things in all keys, and in generating chord progressions, but I think that the easiest way for guitarists to learn their keys is to apply the
shape of the major scale, and work out the notes that way. I'll be posting a lesson on it soon...
Hope that answers your question,
James
