If you want to understand the effectiveness of pressure point manipulation as well as its proper application, a fairly thorough knowledge of neuro/vascular anatomy is required ( if you aren't a biology or med. student you should at least pick up a modern A&P book and compare and contrast it with some of the older anatomical documents/diagrams). Many of the older texts (ex: The Bubishi) use antiquated terms and a lot of mysticism (for example striking points at certain times of the day to cause a desired effect). Pressure point strikes are very real though, and are incorporated in Chinese Chin Na as well as those styles influenced greatly by Okinawan Tuite (Ti): Kojo Ryu, Matsumura Seito Shorin Ryu, and a few others. Proper application of technique is situationally specific, but if ones' knowledge and training are sufficient, then application should pose little problem (no matter the intensity of the confrontation or the opponents skill or mindset). According to my Sensei he doesn't have to be standing in front of you to be used as a guinea pig, and the true test of pressure point skill is its combat efficacy.