"Meaning professional Perl guys too use modules and they rarely roll their own stuff (unless needed)?"

I'm not officially a professional Perl guy, but I promise you, the best of the best use what is already available, as long as it has a good test suite, an extremely high test pass rate, along with very good documentation and even better if the distribution's author is reachable for questions and feedback.

Regarding the "rarely roll their own stuff", that's not just "unless needed". I have written distributions on the CPAN not because I needed it, and not because there are already duplicates, but because I needed/wanted to expand my knowledge on a specific area, and at the time, I had a need for a module that would allow me to gain that experience while writing something that was already written.

Not all of my duplicate efforts have made it to the CPAN, but many have. There's nothing wrong with that, it's just a different way to achieve the same goal. I typically note the other modules that do the same thing in my documentation, and in some cases I've had authors of the similar distributions contact me to discuss my own approach. Re-writing something isn't always a waste of time is what I'm saying here.

I'm not necessarily for re-creating the wheel, so when it comes to the basics and re-learning, knowing completely how to integrate other modules into your code and use other APIs are just as important as being able to do a print "hello, world!\n"; imho.

Just as important however, is understanding and fluently using the common idioms, as some things just aren't worth trying to re-work/reproduce and there are better things to re-invent for learning purposes.