Only one thing

In order to guide the disciple the Sheikh should know only one thing: where he is in spiritual terms. Only if it knows his position, he can lead him to his destination. If you cannot see, he may even know all the classics and the entire Koran by heart, but this will not be of any help to the disciple.

This is the difference between a real Sheikh and a good teacher.

The disciple has already entered into an agreement with the master in Heaven. His name is written in the list of disciples of Sheikh, it is preserved in the divine records.

The membership to the list is visible: it is represented by a light on the head of the disciple. If the Sheikh can see it, he calls him directly.
No matter how long the student will take, sooner or later he will have to reach him. He cannot resist.

The Naqshbandi masters know exactly the number of their students and keep it limited. You can not lead the masses and transmit knowledge to each one, it would not work.
The mystical teaching is transmitted in circles, in our case seven, as in the celestial spheres.