I do from time to time, however I don't post that much so I don't have that much oppurtuntity to do so. Do I think you should? Well, it's you're stake so should be able to choose how you use it, with that said if you're milking the reward pool and other users choose to downvote you to return it to reward pool, well that's their choose of how to use their stake too.
I've been on and off but right now I'm completely refraining from self-upvoting. I'd say you shouldn't upvote more than a couple of your posts a day. Also, never self-upvote comments except on very rare occasions when you want your comment to go up in a long thread of comments because you're making an important announcements or something like that.