I started appreciating Petracchi’s Simplified Higher Technique book a lot more when I decided to skip around and try the exercises in the middle and throughout the book, rather than plowing through from the beginning. I then realized that I had played just about every one of these exercises before at different times as shown to me by different people, and here they were all in one place. Weird. Even something pretty close to the famous freakin ‘vomit’ exercise was in there. I seem to like Petracchi’s version better – it is more practical and seems to help intonation in a better way (exercise #11). Funny how these things sort of come together after a while.
So my recommendation on the Petracchi book is: Start in the middle, skip around, never mind playing any of it in order, and pick and choose which exercises you like and seem to help.