I also don't do a set number of comments per day. I try to make them meaningful. I think that when people are trying to achieve a set number of comments, it can lead to spam. I also don't always post a comment immediately after reading it. Some get me thinking and reflecting on a response.
I like your style. If I know it's a deep article that is going to need extra time to construct a meaningful reply, I open it in another tab and leave that open until I have the chance to give it the attention that it deserves. Then I comment. I appreciate that you focus on quality replies rather than metrics.