I use it to give generally constructive advice. (Perhaps a bit of a tongue in cheek way on occasion, but nothing too rude)
I tend to check for new post comments whenever I land in the UserCP, which is usually whenever I'm checking PMs, processing Friend Requests (I totally hate it when people friend me without at least talking to me first and getting to know me a bit) or just tinkering with my signature or settings. This happens at least once every 3-4 days at least, when I put on my usual spurt of activity and post around a bit in boredom.