Is it customary for students to request leave from their shaykh, or do they wait for the shaykh to grant it automatically?

It is customary for students to ask scholars for an ijazah (authorization), and this is permissible and common among scholars. It is derived from the permissibility of the water given to livestock, for just as water irrigates livestock and land, so too does the ijazah nourish the student of knowledge. Scholars have customarily granted ijazat to their students, examples of which include the ijazah granted by Al-Shumunni to Al-Sallawi, and the ijazah granted by the Mufti of the Shafi'is, Al-Ghazzi, to Ibn Al-Dabbagh.

However, a person's sole concern should not be to obtain an ijazah without accurately mastering what is authorized therein, in terms of pronunciation, and acting upon its contents.