Shaykh Saalih al Fawzaan hafidhahullaah said:
And the scholars give importance to these brief works, authoring them and exerting themselves in keeping them to shorten them and refine them; then they would encourage their students to memorise them so that they should remain fundamental assets for them and a store of provision for them from which they can derive benefit, and through which they bring benefit to others by means of them.
And beginning with these shorter works is the foundation for the students of knowledge, so the student of knowledge should begin by learning little by little, taking from the initial points of knowledge and its fundamentals and then proceeding in stages through it.
So these brief works are the path leading on to the longer works. So it is not possible for the longer works to be understood exept after the brief works have been understood and then the person has preceded on from them in stages. And therefore they said about the meaning of His saying, He the Most High:
But rather be rabbaaniyyoon (wise scholars who cultivate the people) by your teaching them the Book and your studying it. [Soorah Aale Imraan aayah 79]
The word rabbaaniyyoon – they are those who begin with the small matters of knowledge before the greater ones. They cultivate themselves and their students beginning with the smaller matters and moving onto the larger matters, and this is something natural, because all things begin from their roots and their foundations and then they grow bigger and larger after that.
As for the person who pounces upon knowledge from its top, then this person will just tire himself out and not attain anything. Whereas the one who begins with the fundamentals and proceeds in stages, this is the person who, by the permission of Allaah, will be proceeding in the correct way and with sound direction.
(From the introduction to Sharh Usoolith Thalaathah by Shaykh Saalih al Fawzaan, translator Abu Talhah Dawood, taken from www.ittibaa.com)