Complex sentence: The system is quite difficult to learn, requiring in depth study, usually an entire course requiring the reading of several full books is necessary to be able to administer and interpret a Rorschach test appropriately.
Split into simpler sentences: The system is quite difficult to learn, requiring in depth study. Usually an entire course, requiring the reading of several full books, is necessary to be able to administer and interpret a Rorschach test appropriately.