when setting up a specialized routine, I understand you perform the routine no more than twice a week and the duration is two weeks
Is that correct?
And after the two weeks is up, is it advisable to start another specialized routine and keep doing this until all of the bodypart specialized routines have been performed?
Not Dr Darden, but have utilized several of his specialization routines. As far as I have learned (or should I say unlearned?) you are right in the way Dr Darden prescribes them in terms of frequency and length/duration.
My interpretation of specialization routines is to apply them on lagging bodyparts or to break a plateau. I would never do them in succession of one another, even if it’s possible doing so to spice things up.
Pettersson’s concept is a good way to apply the specialization routines.