This book is not to be taken too seriously! In a good way.
I always like to remind people that while there are some rules for how to behave in certain social situations...most of these are general guidelines or suggestions. Mostly I think etiquette is about how to remain as empathetic and kind as possible, eliminating rudeness and callousness whenever possible.
I like this book, I believe Miss Shade has given us very good guidelines as well as including some well meaning humor in it as well. Also...etiquette definitely changes with time!