I think you should do research by reviewing case studies and evaluate how much work is required to run one site, then go from there. Most sites that are making a full-time income are posting 3 times or more per week unless they're in a very low supply and high demand niche. If you do less work upfront, you postpone the results, so if you can post more onto one site aggressively, I'd say, go that route.

Is posting 3 times per week or more (1000+ word articles) going to be feasible for you on each site? If it's feasible, then will you be able to maintain this for 1 year or more?

I did the same thing when I got here, and even though I had a strong work ethic, it was still quite alot required to thrive in my niche. Added to that, if you haven't mastered one, then you are likely to translate the learning curve mistakes onto each site, and it's a pain to go back and fix that.

Just some things to think about. Here is a training that should help: How Often Should You Post on a Blog?

Do you think that’s spreading yourself a bit thin? I have 2 sites.. a well established website and a brand new one. I struggle to keep both going.. I applaud your industriousness!