Scales made out of equally-spaced notes haven’t always been the vogue. During the last thousand years, hundreds of different scales have been used. What makes one different from another?
Tantrum , a piece of software I wrote, shows the out-of-tune-ness of all the major and minor triads available in a 12-note scale with a given tuning:
With this, it’s easy to get a feel for the kinds of trade-offs there are between scales; some scales will be very good for a small number of triads, others will be acceptable (but not great) for a large number of triads.