I'm critical of the many bushcraft and survival manuals as well as some of the bush food books that seem to merely parrot information gathered from other sources.
Lofty Wiseman wrote the sas survival guide which has been widely copied. I have no doubt that everything in his book is based on first hand experience, but the numerous books that copy his format make me question whether the authors have actually tried everything they are writing about.
It took me a long time to consistently produce an ember with the hand drill and bow drill, because I had been following the instructions of books and diagrams (no pictures of the authors actually performing the technique which should have been a warning sign.)
Yet on the weekend I was able to instruct my brother in law in both fire techniques successfully by including instructions about body position left out of the manuals.
Similarly, bush food books sometimes leave out details such as only part of the leaf can be eaten, or only at certain times, which makes me suspect that it is not first hand experience.
A very long winded way of saying beware the manual with sketchy instructions and no photos. Save yourself a lot of time by sourcing the good books, many listed on the forum, or even better by getting to a meet and learning first hand.