Successful blogging seems to requires focus. I base this conclusion on the usual list of hot blogs in WordPress. A high-traffic blog is usually a nexus for posting, talking, thinking about a single topic or theme. Technology. Food. Sports.
However, it also appears that successful bloggers are allowed one recurring outlier. That’s how we get David Churbuck’s blog: “Comments on media, technology, marketing and clamming strategies”. If you know David, the first three are all one subject mashed together. The clams are the outlier. The Venture Capital blog I read talks about business and throws in the odd music post.
I think readers will allow you one outlier. After that the blog either becomes Mildly Interesting to Everyone but Fascinating to Noone, or the blogger has to cobble together some artificial focus: “This Blog’s About About Eclecticism!” or “Reassembler!” or some such nonsense.