Often, I write to exorcise something consuming my thoughts. This is commonly what lies behind the more vitriolic rants found here. I find it to be a healthy outlet for great anger. Other people vent it at strangers with inconsequential near-car accidents as a pretext, but I can't do that, so I do it here. I don't know if that makes for my best work, but it makes for my most motivated work. I wish I always had such obvious stuff to write about.
Something unfortunate is that I never have felt at ease writing about the same thing twice. I'll cover something at length if it was only mentioned in brief, or I'll come at something from a fresh angle or with a different perspective. I just won't do the same thing twice. Regrettably, that precludes me from venting my anger about something again, leaving it to fester if it returns. Return it does, and all too often for my liking.