Hybrid attack splitting

[philsmd]

the only ways to reduce the time needed for one chunck even further than -l 1 is to use lower -n/-u values (which affects the speed) or to reduce the number of hashes (which is also counter-productive in general if you need to test all of them)

Maybe the best answer to your question is a counterquestion: Do you really need to bruteforce bcrypt hashes? Maybe there are better alternatives than mask attack which you didn't exploit yet?