Narrow and Deep, not Broad and Shallow. Jessica Livingston of Y Combinator describes how Sales differs from Marketing and makes the case that Start-ups should focus on the former not the latter. It really boils down to how effective your product is. Going narrow and deep allows you to engage with passionate users, creating a feedback loop that allows you to make your product better. Going broad and shallow, too early, with a mediocre product, increases the chances (guarantees?) that it will just bounce off a bunch of uninterested potential users.
You should check out the post , it’s a quick read.