We have a paid membership to Linkvana and have been using it for several months now. There isn't a limit to the number of blogs you can submit. You can create a Project (i.e a domain), and select to publish 3-5 blog posts per day. You can then create ANOTHER project with the same domain (or a subpage on your domain) and publish posts at the same time. The site says the articles need to be 100+ words, all the outsourced articles we get from them are between 105-115 words, but I've had a few articles less than 100 words get published.