The zsh shell is not only very powerful, but can also be confusing, expecially when it comes to choosing between .zprofile, .zshenv, .zshrc files to configure the $PATH. As there are divergent opinions on Stack Overflow and web blogs, hopefully this gist can help to provide more clarification.
The most detailed background explanation I found is the gist by Linerre. While I really recommand to read it, the key aspect is that the configuration files are processed in the order .zshenv, .zprofile and .zshrc, as on macOS a zsh shell is always treaded as a login shell. MacOS further changes the $PATH after the processing of .zshenv with the path_helper, which could lead to unexpected behaviour when following the the zsh documentation which suggests to configure the $PATH in .zshenv.
Therfore, I am configuring zsh in the following way: