> I'd like to know if there are any resources about the practical
> everyday use of CAD.
reacting to tools, you're not really considering exactly what that
tool is doing (and not doing) for you.
Once you begin customizing (actually developing software or at least
scripts) you don't understand how the framework operates. But when you
are trying to program some functionality, you quickly understand the
limitation or simplicity of it.
Think of a task that would make your job easier. Then write a script
to do it. Extra points if it's so easy you can explain it and let
someone else use it in a sentence. Then donate your work and your
advice to newbies. :)