The exhaustive list is longer than I have patience for, here's one example: understanding how the parse and lex steps work, and what is accomplished is useful without knowing how to pseudocode a recursive decent parser. It's worthwhile to write said parsing algorithm once in your life, it's not necessary to keep that knowledge warm in your head throughout your career.
Hmm, I guess I don't know what "understanding how the parse and lex steps work" would consist of that didn't involve being able to pseudocode at least some kind of parser, of which the recursive-descent type is the simplest. But maybe I'm blinded by having spent too much time writing parsers. Or maybe you mean "knowing how" in some kind of total back-of-the-hand mastery sense, as opposed to "you could eventually get it to work"?
