Like the title it self, "The First 20 Hours: How To Learn Anything", you can actually learn from this book only the first 2-3 chapter, the rest is up to you to read it or not. It's optional.
The 2-3 first chapter on this book, is pretty much the theory how to do skill acquisition in a fast way, the critical point like 10 main point of how to learn fast is here in the first chapter.
The other chapter is merely about the writer, Josh Kaufman experience itself when learning those skill.
I found it some of them like the "Touch-type" and "Learn Programming" chapter to be interesting, its even make me want to learn the Colemak keyboard layout right now.
Fun fact is that, i had watch an TedX video about this (First 20 Hours), turns out it's written here as well on the book, which he demonstrate him playing ukulele.
It's not necessary to read the chapters were the author uses all the relevant points outlined in the prior chapters on Skill Acquisition to acquire a number of skills on his to-do list... The Afterword is insightful as it reaffirms the importance of the first chapters. Good Read💡💡💡💡💡
Good read. Certainly want to learn some coding, touch type, and play ukulele