I think up until recently, homebrew was also recommending incorrect instructions for fish shell users in a similar sounding way. The instructions basically said

I think up until recently, homebrew was also recommending incorrect instructions for fish shell users in a similar sounding way. The instructions basically said add "fish_add_path /usr/local/bin" to your config.fish file, but in actual fact you only need to run fish_add_path once and its added permanently to your $PATH for all your future sessions, as well as your current session. I only realised when I finally got fed up with my terminal taking several seconds to start, I dug into why and found that my $PATH had something crazy like >1000 items with the homebrew path taking up pretty much all of them.