We favor the variety and relevance of the exercises in relation to the actual tests rather than a large number of exercises which do not always correspond to what we encounter in an exam situation. The first concern is efficiency. Generally speaking, whatever the type of test, it is much less complicated than you imagine.
We have decided to give the explanations and the answer to an item immediately after it or in the same chapter. This makes it easier to understand the mechanisms by avoiding having to go back and forth between the 1st and 2nd parts of the book, as is the case in the vast majority of books devoted to selection tests.