Well spending A LOT of time in reading I got some opinion. I think the that more 150-200 page total is a BAD book.
WHY? Because you are loosing structure of information in such a book. The idea or method or technique or whatever should be easy to understand. You can have many thing to say, but if you writing something it should be something in conclusion not a bla bla bla.
Does it mean if you have to say a lot you should CUT it? Not at all! Idea is making really good structure of data and data visualisation. Making a book it's not a RACE - make it short, informative - easy to use. If you have Many thing to say, make a "categories" chapters of books - not chapters inside of book.
One of greatest modern professors of physics Stephen Hawking "each equation halves the book sales rule", I believe the Size of book affect almost the same rule.
So make it SHORT, INFORMATIVE and EASY - do not think about time because if it's good book, yuo will present it fro many future generations ahead.
