Normally the first layer that is created is Black lines by default but as we make more layers, each new one gets a new color. The problem is that most of these NEW colors are not very visible on the most used background being white. Since the first days I have requested that there be a choice to lock the color of the new layers created to be Black or a chosen color unless the user wants to change it. At present, every file that I work on has about 20+ layer s and I have to change color at least 15 times to see my outlines, etc.
I have used AI since the 88 version.