The advice from published authors I know is that the highest correlation with eventually getting published is to have a weekly (or regular) cadence with an intimate critique group of small size. The critiques themselves are useful, but even more important is the social pressure to produce.
I've always wondered how famous authors seemed to all hang out with each other, like C.S. Lewis and Tolkien. I realized the question was poorly formed: famous authors tend to cluster because they got to know each other before they were famous. They improved their craft together, and each person's success levels up the group.