In the blogosphere, there is something called blog etiquette. Blog etiquette is sometimes referred to those rules which other bloggers would like to see everyone else abide by. In a sense, blog etiquette is a limiting factor on blogs. One of the key benefits of any blog is its ability to be anything it wants to be. Blogs have managed to break any number of rules in the publishing market. Blogs can also be used to break through standards and norms in the blogosphere.
If you have a blog and want to post once every two months, go for it. Your blog will succeed based on the depth and richness of the content, not how often you post.
See more about similar issues @ ... http://www.myshingle.com/my_shingle/2005/06/shortcuts_so_yo.html