I don't think you really MUST have more articles, but it's just a pattern I'm going with. Personally, I plan to continue building content on each of these sites each month rather than building more and more of them every month (though I will add a few here and there of course). If it was mine, I'd keep pumping content into it regularly. Also, the content I'm publishing is not just 5-6 articles all focusing on exactly the right keyword for that site. Instead, I'm publishing articles that are all in the same general category (like weight loss, self improvement, finance). I think it looks a lot more natural.
Although I've got multiple scrapebox licenses, I'm just using it to scrape URL PR and OBL. Then I'm feeding those into No Hands SEO, setting it on a small number of threads and letting it drip feed all the web 2.0 sites that way. It's got comments + trackbacks, with unique comments that I put in, and is posting at a rate of about 2-10 links per site per day.
I'm not seeing the links updating very often on Majestic or OSE. It's like they're both taking 45-60 days to update or something, so don't sweat that in the short term.