Comment by zelphirkalt

Usually one does not need to know all the rules of specificity in a project with sane style sheets. Often it is enough to know what styling applies to a parent element and then make the selector more specific by addressing the child element, or if element at the same level, make the selector more specific by adding more detail to where that element is located in the DOM to the selector. Then one automatically has something more specific.

In other cases one can look up how it values id selector for example, or watch the immediate result in the browser, as one adds such a selector.

I am guessing, that over time people, who deal a lot with CSS, will learn the specificity rules automatically.