Can someone tell me if this book is 100% all right?

He says that you can avoid czerny or hanon

What do you think about parallel sets?

And the Gravity Drop?

Please tell me

Never heard of this before. Give me about 5 months and I will give you my opinion (5 months because I am swamped with reading for my classes)

I have read this book from first to last page and even though he has a lot of points, you should not count that everything in this book works for everyone. He makes it a little too easy when he assumes that everyone learns faster and better hands separated, in full speed from the beginning and by memorizing everything by heart. For me, learning both hands together with a very slow tempo is the fastest way for me. But the reason is that I rely on muscle memory more than anything (as the case it for most people).

But when he comes to Hanon and Czerny, I think he is right. You do not earn much from spending endless of hours of these musically brain dead exercises unless you think it is fun. And I do not.

Gravity drop is the correct thing to achieve power and I do not think anyone think this can be wrong.