Is it permissible to shorten the period of teaching the Quran in the kuttab (traditional Quranic school) from the duration specified by the Awqaf (Endowments Ministry) if that shorter period is sufficient, and what is the ruling on the salary in this case?

The teacher in schools and Qur'anic schools is considered a private employee. He must remain at his workplace until the end of his designated working hours because his services during this time are owned by the employer. If he leaves before the end of the time without permission, his wages will be reduced accordingly.