Very good questions. I also has the same challenges.
If you are talking about building relationship with your subscribers, perhaps using email marketing newsletter is much better because it is all pre-written and the new subscribers gets the first newsletter from the beginning as well.
If you are talking about bloging. Perhaps 4 times is the most ideal approach (according to a research I done previously).
To maximize our blog, create 1 blog post and we should submit it to other PR, directory and also on others blogs to drive more traffic.