> Each of the Intel intrinsic functions are well documented but figuring out which ones you need out of the 600 or so available functions is not easy.

So true. One of the most valuable skill to grow when using Intel intrinsics is a fluent navigation and intuition of the intrinsics library.

Nowadays things are much easier though, there are a lot of indexing websites and softwares where you can query, search, find intrinsics very quickly. Intel had an interactive intrinsics doc already 10 years ago.