I think that the four thoughts are actually a practice to accompany a practitioner during his/her whole life.
Yes, definitely, as is Ngondro once a person gets permission to start it.
Also lojong in general is very helpful even if only practiced intermittently.
Another thing I want to point out is that the term "beginner" does automatically mean a person who is not serious about practicing Dharma. It just means that the person hasn't yet been practicing Dharma for very long. Everyone has to start somewhere. Even Milarepa was a beginner at one point.
I know that on the internet people are willing to fight to the death over very exciting words such as "mahamudra" and "dharmakaya;" however, being helpful to beginners can be just as important because it's a manifestation of bodhichitta, which should always be present in all sincere practitioners.
In any case I had hoped that people in this thread would say things like "In the Nyingma tradition, people usually practice X, Y, and Z before they start Ngondro; In the Sakya tradition, beginners usually practice A, B, and C; etc."
But whatever. I realize that using the word "beginner" doesn't get people as riled up as the titles "intense Dzogchen trivia session" or "top-secret Vajrayogini saddhana revealed!" would.