Like the other books in this Method, the unique presentation of following sets of exercise drills with etudes emphasizing the same material, makes the material enticing and engaging. This book explores the often over-looked subjects of the Low and High Registers in clear, well-balanced and progressive exercises which are then integrated within the entire spectrum of the trumpet’s range.
Plog also mentions in the Introduction that powerful playing should also be practiced by playing in Book 1, his Warmup Exercises and Etudes Book, with a forte and fortissimo delivery – within reason. One has presumably already made good associations with that music and therefore would play it in a free and balanced manner. That is the delivery you want to bring to your fortissimo playing in both Low and High registers.
Then the material in Book 6 will be supplemental. And these exercises are superbly constructed to pinpoint and refine the extreme registers with precision and care.