you know that the information is going to be true.
Not everything you read has to be true. I've seen way too many fish books (when I got my first tank and was trying to learn from books) that gave terrible advice & ridiculous stocking levels. In most cases, it is strictly someone's opinion of how things should be done and has no scientific base. You or I could easily write a fish book and get it published but there's no saying that everything in it would be true.
I just grabbed the first fish book I bought off the shelf. Under Suggestions for Stocking for a 20 gallon tank it says that 3 to 10 days after setting up the tank (no previous mention of cycling, just letting the filter run until the water isn't cloudy any more), to add 2 flying foxes and a brushy nose catfish. After 10 more days, add 7 neon tetras, 5 black phantom tetras (2 male & 3 female), 5 harlequin rasboras, 2 dwarf gouramis (a pair) and 3 corys. After 4 more weeks you add 4 guppies or 4 platies (2 pair).
First, even if the first 3 fish made it through the first ammonia spike, when you added 22 more fish 10 days later you would either have to be changing water 2 or more times a day or lose a lot of fish. Lastly, adding 2 pair of either guppies or platies is not a good idea. The best mix is 1 male to 2 or 3 females. With 2 pair, the males would harass the females to death.
That was one of 4 stocking scenarios for a 20 gallon tank (all severely overstocked). The last one was my favorite though. Once again it started with the flying foxes and BN (all started that way). After 10 days, you added 7 neons, 5 rosy tetras or red phantom tetras and 3 corys. Then the last addition to the tank was, get this, 3 bettas, a male and 2 females. Now that would make for an interesting tank. How long do you think the 2 female bettas would last.
Another scheme for a 50 gallon tank listed 20 neons, 3 angels along with 7 nice tiger barbs. Not a good mix either considering that neons are the natural prey of angels and tiger barbs would most likely eventually kill the angels.
By the way, the title of this book is
Tropical Fish by Peter Stadelmann and Lee Finley. As I said, I'll stick to the internet for my fish information. Forums like this are a much better source of info than books.