There is alot of similarity between this story, making iOS apps and making AdSense websites 7-8 years ago. One could slap a website together in a week, and one would see the revenue slowly but surely coming in and going up. The strategy of "making a website every week", and the total will make up for it worked too, for a while. Nowadays, every niche is crowded, and often more professionalised with several persons working on it, Google taking drastic measures to penalise spam-techniques... and the 1-week effort websites (even if you have good, quality content -- but it's just little) will get you nowhere anymore. It is almost, exactly the same story.