It is a great and special avodah to learn the commentary of Rashi on Chumash. All of his words are written with ruach hakodesh. In his peirush, he turns the Torah into metzius, reality. Through realistic thought, we can reach greater depths and deeper levels. Avraham Avinu was absolute reality, but a totally different concept of reality than we may have of him.
The derech halimud of Rashi’s commentary is not in the form of a mahalach, a uniform approach to the whole parashah, or even to a single pasuk, because every “reality” stands on its own; likewise, every comment and commentary of Rashi stands on its own. In each comment of Rashi, there is tremendous depth, but the way to learn his words is not through “depth,” but rather through the approach of “reality,” and from there, with time, to attain profundity and internality.
We are used to learning peirush Rashi together with the weekly review of the parashas hashavuah — shnayim mikra v’echad Targum. We generally give a cursory glance at his words, especially those pieces that we know from before. This is due to our erroneous attitude that Rashi, kivyachol, gives us the “literal” explanation of divrei Torah. This approach is mistaken. When we delve into his words, we will find that even in the peirushim that we’re familiar with and that appear to us as simple and superficial, lies tremendous depth of understanding, so much so that we could spend a whole week on his peirush of just one pasuk.