A few months ago I decided to focus on high quality comments after feeling like I was contributing to the HN noise a bit too much.
As a proxy for that, I tracked my average comment score, trying to get it above 10.
Today it's 14.93, which is quite high - only 4 of the top 100 are higher.
I think my comment quality has risen substantially, but I also subconsciously started making decisions based on score - not posting on topics that were sliding down the front page, or where there were already hundreds of comments but I did have something to say.
In short, the gamification overtook the original goal, and the tail was wagging the dog.
I've now started using a much simpler method - taking a deep breath before hitting reply, and trashing the comment if I don't think I'm adding anything to the conversation. I like this way more.