This has always bothered me. In what's typically called a 13th chord, the 11th is almost always omitted because it either clashes, or it changes the chord into

This has always bothered me. In what's typically called a 13th chord, the 11th is almost always omitted because it either clashes, or it changes the chord into something completely different. Stacking 3rds doesn't actually explain how jazz chords work. And it tends to produce corny voicings. To make an analogy with computers, it feels like the classical notation is an abstraction layer which has been extended beyond its usefulness.