Fallow periods are normal and healthy, I think, and help prevent burnout. You need to take time to "take in" as well as "put out." If you're always putting out and don't leave time to take in, you end up with nothing to say and no inspiration.
You can observe this pattern with professional musicians, especially singer-songwriters. When I lived near Boston in the 1980s I watched the careers of Tracy Chapman, Shawn Colvin, John Gorka, Suzanne Vega, and Nanci Griffith develop from the start. (Tracy Chapman started out as a street singer; I used to hang out on the street in Harvard Square to listen to her. John Gorka was an opening act for Nanci Griffith, and eventually people started going to her concerts so they could hear him first) Their first albums were big hits, because they had spent years living, writing, revising, throwing out the bad, keeping and improving the good, and so on. But once they had record contracts and had to churn out albums year after year, the quality of their material (mostly) went down. They didn't have time to live life and build up material between albums. Many novelists have the same problem, with the exception of Joyce Carol Oates, I don't know how she writes so many books without burning out.
One of the reasons I've never wanted to have a blog of my own is because I need time to live, digest things, and think them over before I write about them. If I had a blog I'd probably only have one entry every two or three months. It's easier for me to just leave comments on other people's blogs
