Most of the someone else's I have read has been in stuff from CPAN, and I recall it as pretty good. I have written some pretty bad Perl, and wish that I had encountered the O'Reilly Perl Best Practices long before I did.
Perl's "layering" is one of its most brilliant features. You start learning Perl in layers; achieve some fluency and effectiveness and understanding of the general principles - and will still have many layers and sets of features that you can dig into as you progress. The set of O'Reilly books was amazing for this. Still is. But the documentation itself was amazing also. Still is. That's one problem with Raku: Can raku ever get to this level?
This is important as a powerful tool for a powerful programmer.
I always contrast this to C++ - where you are dangerous, too dangerous, until you have learned a huge amount "of the language" (and good luck understanding it). Or BASIC, where... there isn't much.
