Multiple blogs and strategy

I want just your opinion,
I have several blogs (blogger) with adsense. I'm writting around 20 articles per blogger, without doing any advertissement at all, and i don't know if it is a good strategy on the long term. The last month I make around 985 doll the month, 4 of them give me the most, and the other one add a lot of dollars.
I may have 20-25- on which I have adsense (not sure to tell the truth), I don't check "google analytics, google tools…" what I doing it's written, add adsense and…
Multiple blogs and strategy

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