The gemara (see Rashi) interprets Yosef’s instruction to his brothers, “Al tirgizu baderech,” to mean that they should not learn Torah en route home. Although there is a mitzvah to learn on the road, Yosef warned his brothers not to learn “b’omko shel halacha,” in depth, lest they lose their way (Rashi). You can’t concentrate on a deep sugya and concentrate on driving at the same time.
Let’s put this in context: the brothers had just discovered that the Egyptian official who they thought was going to enslave them was none other than their long lost brother Yosef -- their entire world was turned on its head. They were in such a great state of shock that the Midrash writes that they dropped dead on the spot -- Hashem had to revive them through a techiyas ha’meisim. If any of us had such an experience you can bet your last dollar that it would be the single topic of conversation in our lives for days if not weeks.
Yet, such was the level of the shevatim, explains the Brisker Rav, that Yosef had to warn them not to spend their time immediately afterward learning b’iyun on the road. What happened happened – talking about it would not change a thing or produce any benefit. Back to the world of the Ketzos, the Reb Chaim, R’ Akiva Eiger!