It's an interesting book and definitely trains you to keep an eye on the relationships between different ingredients. And especially the continua between different foods made of the same things in different ratios.

Unfortunately a lot of the recipes in that book are not very good! When settling the ratios he prioritized small, clean numbers to make the relationships clear. But those aren't guaranteed to be an optimal recipe. It's simply more likely that the best custard for example is 28:15 or 11:5 or whatever than it is precisely 2:1. Ditto every single thing in the book.

It is a good starting point for learning how baked goods work, developing intuition for how changing ingredients influence the final product. Virtually none of them are excellent ratios though.