I mean....I think it goes without saying that you shouldn't post all of something you intend to publish because why buy if you can read for free. But putting teasers can also generate interest. Sure there's always a risk, but there's benefits too. I don't post things I want for publishing, but I'll post other stuff, just so I don't have to take the story down later for a publisher becuase that's the real trouble. Publishers don't want a copy existing on the internet.