William Llewellyn's book is a massive reason as to why many people are cycling awfully....
Just because you write a book - it does NOT make you an expert!
The man knows his shit. And in my early opinion, awful cycles (within reason). Perhaps improper blood monitoring, AI use, PCT, etc. are what make these reactions awful. Everyone reacts differently. There is no ubiquitous approach from one man to the next. These guys just coming in and going against their own initial research to please their peers on the forum end up doing exactly what they wanted to do on their first cycle the second go. And probably find the results on target of their goals. I think the book is extremely detailed and comprehensive. I recommend it to rookies and vets.
Who has done more research than the author? I know of no one who has an integral approach to AAS studies. I personally know TRT Doctor's and I have read about many. Most of them are naive. I just feel like you cannot prescribe cycles on people with information regarding age weight BF and bloods. There are many more variables here. And when that person reads valid information for them selves, they can use their own reasoning and logic.