Makiwara training is only one of many methods used in 'hojo undo.' The book 'The Art of Hojo Undo' has a lot of excellent information on this ancient style of training that was developed as part of the Okinawan fighting methods now known as karate. The exercises used in hojo undo are highly functional, and closely relate to the types of movement that you use in kata. The book contains information and diagrams for not only various exercises, but describes related techniques, and how to construct equipment. The author also draws similarities between various techniques used in different styles, how the exercises benefit techniques, and even devotes a chapter to warmup exercises, which is important in injury prevention. Last, but not least, there are some details on the history of karate as well as the differences between "traditional karate" and today's modernized "sport karate".
The ancient training methods described in this book show you how the old masters taught their students to not only toughen their bodies, but toughen their minds, as well as develop spiritual discipline through dedicated training. This helped them become complete warriors. Not only that, the training methods are of great benefit to almost any martial arts style, even various types of wrestling and other grappling arts, because of the benefit to grip strength and explosiveness.