This approach tends to work better for articles that are jam packed with information and/or those that take a broad, aerial view of the topic, but it can also work with articles that are a close up view of one specific topic. For example, I've written many articles on how to create an effective resource box, and from that one very laser beamed topic I have branched off articles on extremely specific elements of that already specific topic. I assure you, no matter what your article is about, you can write about it more in depth in a new article.
I know that it can be mentally taxing to try to come up with new ideas for articles. After a while you may feel like you've written about every aspect of your subject that you possibly can. Here's some good news__you don't always need to come up with new writing ideas. Sometimes all you need to do is look at your previous articles and go more in depth. Your Homework: Look at your last 5 articles In each article, search for at least one point that you covered that you could cover more in depth in a new article. No matter what your article was about, you should be able to dig a little deeper on every major point you make in your articles. You may even find some minor points that could use elaboration.