For those of you who want to experience 24-tone composition, listen to Angine de Poitrine:

https://www.youtube.com/watch?v=0Ssi-9wS1so

12-tone/serialism was a seriously dire period in modern art music. After Romanticism ran its course and maxed out the tonal possibilities of music that attempted to convey emotion, 12-tone came along to provide a rigid intellectual structure to music that had existed in the baroque and classical periods, but had been blown away by the Romantics and post-Romantics.

Unfortunately it also made listening to music a purely intellectual exercise as well, and a painful one for folks who expect tonality to be a part of any music they want to sit through.

Thankfully folks like Steve Reich, Terry Riley, and Philip Glass came along to embrace the rigid structure and intellectual design approach, but to return tonality as a core principle with Minimalism. Art Music was listenable again.