The obvious exception in the western system would be the blues scale, which arguably has 9 tones (7 equal tempered notes, plus a just tempered 3rd and 7th).
And Indian ragas break all of these rules. They have scales that don't have 8 notes, scales that don't use equal temperament, and even a few scales that don't repeat on octaves.
Math checks out.
> So yes, the 12-tone scale is a universal thing -
I don't follow the logic here though. It's certainly true that a 12-tone / Chromatic scale is ubiquitous within the Western Music tradition .. but the universe is reportedly a little larger.
Even Western Music includes exceptions like the 9-note augmented scale, though the argument can be made that it's a 12-scale with 3 bits "missing" - not a case that can be made about a non-western 7 note percussive scale.
Also the so-called "Western music" standardized on 12 tones very late in the process, long after the Chinese figured it out.
> a 12-scale with 3 bits "missing"
That's all scales, even the "non-Western" ones. Microtonality is added to the standard 12 tone to add tone effects. (Synthesizers in pop music do the same trick.)
https://www.huygens-fokker.org/scala/
Note also that certain musical traditions were suppressed or eradicated due to their unfortunate habit of using dissonant notes such as minor seconds, as opposed to the consonant traids favored by a particular group recently in power around the world. Happy Easter!