IMO
It means they sometimes see projects that are close and they know how to get it across the finish line (e.g. change from third to first person, or move the order of the opening around, or change the age of the protag to fit a different market, or ratchet up one element and downplay another, or or or).... And sometimes they see a project that is close but they aren't sure what it needs, exactly, to sell.
They are thinking in terms of the readers and the market, because fitting those pieces together will get a bigger sale. We usually think in terms of story and character, which is a different angle of approach.
It means they sometimes see projects that are close and they know how to get it across the finish line (e.g. change from third to first person, or move the order of the opening around, or change the age of the protag to fit a different market, or ratchet up one element and downplay another, or or or).... And sometimes they see a project that is close but they aren't sure what it needs, exactly, to sell.
They are thinking in terms of the readers and the market, because fitting those pieces together will get a bigger sale. We usually think in terms of story and character, which is a different angle of approach.