This is an interesting question, but lucid dreaming is very hard to quantify. As an example, I have always had very good dream control from probably my 3rd or 4th lucid dream, I can change the environment right in front of my eyes, teleport to a different scene, slow down or speed up time, shrink myself to the size of a sub-atomic level, or fly through the universe faster than light, in that sense I think I'm fairly advanced. But when it comes to LD induction, I would class myself as a beginner, DILD's are extremely infrequent, and WILD's are successful around 20% of the time. So it may be necessary for separate categories such as, but not limited to, Induction, Dream Control, Dream Stability/Dream Length etc.