One thing I didn't see mentioned, which is a pet peeve of mine, was how it's not ideal to use just hue or just lightness when you're supposed to read values from a dataset.

Case in point:

https://blog.datawrapper.de/wp-content/uploads/2021/01/full-...

Which slice of the pie represents Japan? Probably the leftmost, but they happen to be few and ordered, so it's easy to infer that.

Now imagine this is a map, not a pie chart and you don't know where Japan is. Pretty hard to tell those very similar blues apart.

One way out of this is to use two lightness levels per hue and sufficiently distant colours:

https://www.researchgate.net/profile/Md-Sariful-Islam-6/publ...