IPC::Run3::Shell already looks much better, but I'd opt to use it primarily for non-standard executables which can't be implemented in Perl.

Agreed, and I wouldn't normally shell out to things that Perl can do natively either. Sometimes, if I'm writing a one-off script that's not meant for production, I might call find, but then again I've started using File::Find::Rule more often (even though I've measured it and it's not nearly as fast as File::Find or find). Anyway, I grepped my code and here are two examples of how I've actually used the module, in the first one I remember that in that particular case, simply calling the convert program was much faster to implement than getting Image::Magick set up. Especially if the scripts are not meant for a production environment, speed of development is often what it's about; depending on what one has the most experience with, remembering or looking up the command-line arguments can be faster than finding the appropriate Perl module.

use IPC::Run3::Shell { fail_on_stderr=>1 }, qw/convert/;
convert $img, '-auto-orient', '-resize', '300x300', $thumb;

use IPC::Run3::Shell qw/gs/;
gs({fail_on_stderr=>1,show_cmd=>1},
    '-o',$OUTPUT, '-sDEVICE=pdfwrite', ..., '-f',$INPUT);
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Update: Minor re-wording.