I've found through personal experience that you definitely CAN spread yourself too thin. You know all those professional bloggers who make five figures a month? They don't own as many blogs as I do. They know what they're doing. They focused on 1-3 niche topics where they would be able to blog and blog and blog without quick and easy burnout. Not me. Oh no.
You see, I'm the type of guy who buys a domain name and feels compelled to host it with blog software as soon as possible. Some of these domains I thought I would sell, and eventually I will. But in the meantime, I have put this huge burden on my shoulders to maintain too many blogs on too many topics. Despite what my parents think, I simply do not have that much to say on a daily basis.
So how do like me find a way to overcome overwhelmingly random interests? Pick three domains to be blogs. Make one your personal blog. You can take full credit for this personal blog if you want, or you can keep it anonymous. Use this blog to vomit all your randomness into. Who knows? Maybe you'll build a following over time. Beyond your personal blog, pick two topics max and dedicate yourself to covering them. Give yourself a full year of blogging on these three topics before adding another, and add only one new blog per year IF ANY.
This may seem like it will take forever to establish yourself online, but you'll do far better than I started out if you limit the number of blogs you own and operate. It's okay to cover every topic under the sun as long as you isolate that blog from your niche blogs. There's really no reason to own and operate 7-11 blogs unless you miraculously build a staff of bloggers to do the heavy lifting for you.
You'll do well to learn how to moderate yourself from the beginning. You'll save yourself a lot of stress and frustration if you do. Best of luck, and happy blogging!