When learning about European classical music, it's heptatonic scales. The pentatonic scale is also very well known and widely used in folk music in different parts of the world. However, before I started reading in Wikipedia about hexatonic scales, the only hexatonic scale I had heard about was the whole-tone scale. The hexatonic scale that you get by throwing out one of the notes from the diatonic scale so that it becomes atritonic (or by adding one note to the pentatonic scale) seems to be less well known than its neighbors. Although, just like those other two, it can be derived from a chain of perfect fifths.
What I mean is the scale which has the following intervals between notes: 1 semitone, 2 semitones, 2 semitones, 3 semitones, 2 semitones, 2 semitones.
I started thinking about it in the context of algorithmic composition. This 122322 scale is much more flexible and rich than the 22323 pentatonic scale. There is this semitone and you can get more interesting melodies out of it. But, unlike with the 1221222 heptatonic scale, you do not have tritones anywhere. If I want to avoid tritones in melody and harmony, this is a very good thing since it ensures that any random bunch of notes that my algorithm outputs is guaranteed to not contain a tritone.
There are of course some disadvantages... The one that I notice is that it's not possible to play two major or minor chords that are two semitones apart. However, for example, if we want to play F major and G major chords, we can just play A-C interval and G major chord, or F major chord and G-D interval, and to my musically untrained ears, those compromises sound almost as good as the two full chords. And, whatever the disadvantages are harmony-wise, in pentatonic it's even worse, right?
Are there any practical or historical reasons why the 122322 scale is so little-known, while the two nearest neighbors 22323 and 1221222 are in wide use? Does it have something to do with the fact that 5 and 7 are prime numbers while 6 is not? Does it have something to do with the history of musical instruments?
Or IS hexatonic little-known? I do not have much music background, only took a couple of music theory and harmony classes at the uni, so maybe I am mistaken and the hexatonic scale is actually more widely used than I think? Do you know any pieces that use this scale? (Especially folk melodies, early music or classical compositions.)