Hi! As I understand it from the book, those 23 days take into account rest days; so we have Day 1 (80% of 1RM), rest, Day 3 (60% of 1RM), rest, Day 5 (60% of 1RM), rest...
The original routine in T-Nation is longer, but what I understand from the book is that every program in the sequence is meant to be made in about 1 month each one (pg. 193). We´de finish with Day 23 (80% of 1RM) and 10x5.
Maybe I didn´t understand what Chad recommends or it´s just that you are following the guidelines from the article and not from the book.