Hmm... don't drive something with its own child, or with the child of a child, etc..
They are easy to create, but just remember that the tree gets updated sequentially.
If I have a sketch, then I make a pad of that sketch, then I put a sketch on a surface of the pad, then I make a pocket with the sketch on the surface of the pad, I can't go redefine the first sketch to have it reference the pocket without creating an update cycle. Why? It's going sequentially. Sketch.1 depends on something that depends on Sketch.1, and it gets stuck.
Avoiding Update Cycles requires careful understanding and planning of your design. As Configurator states, you simply need to make sure that your geometry doesn't rely on each other. That's sometimes easier said than done, but once understood and followed, becomes second nature. If done properly, it results in an easy to understand model. If done poorly, it results in a large number of isolated elements, and the model becomes a total mess for anyone downstream who attempts to use it.
