I'm late to the discussion but, yeah no, if I'm writing for free, it's going to be generally small scale things. Nothing like...40k in size. That'd be too much time, effort, and energy to expend for the benefit of getting people aware of my work, and even then, what stops those other people from expecting me to take work for free?

Though, on a note, my mentality is this: if publishers and others wanting submissions expect a long piece of work, they can't get picky.