I’ve been thinking about this, too.

I’ve been thinking about this, too. I decided pretty quickly that if I submit something to a publication then it should be free. If I write something on an important/political issue, then I make it free. When I write something funny or about sex, I lock it from the start. Sex and satire are my main interest. But if a story doesn’t gain much traction after a week, I make it free. That seems to be working pretty well. :)