Once I asked Archimandrite Cyril (Pavlov): why do some brothers from the monastery leave? He says:

Once I asked Archimandrite Cyril (Pavlov): why do some brothers from the monastery leave? He says: "Remember what Bishop Ignatius said: the monk's fall begins only with the abandonment of his blessed monastic rule." In the Lavra there was a rule: three canons, an akathist to the Savior (on Friday the Akathist of the Mother of God), a chapter of the Gospel, two chapters of the Apostolic Epistles and one kathisma. 

This practice was for many years, it even spread to Optina desert and other monasteries of the Orthodox Church. And I saw with my own eyes that Father Cyril himself strictly observed the rule. "Die, and fulfill the rule," are his words. An hour before the fraternal dinner, exactly at noon, he came into the cell, and the reading of the monastic rule began. The novices, monks - all came to his cell for the rule, they even stood in the corridor...

St. Isaac the Syrian said that the rule at the Last Judgment would stand between you and the devil like a copper wall. For the omission of the rule, we give entrance to the soul of demons. Let the rule be small, but always executable.