What is the cause of the significant, prolonged, and recurrent mental wandering during prayer, study, and at all times, despite long hours of studying, maintaining regular litanies (awrad), and reading the Quran?

Satan disperses one's resolve with matters that distract their mind from their regular devotions and duties. The remedy for this lies in relying upon Allah and knowing that benefit and harm are in His hand alone, which brings tranquility to the heart and keeps one occupied with the worship of Allah. One cannot do without frequent remembrance of Allah Almighty, which brings peace to the heart, comfort to the soul, and forgiveness of sins. Also, the companionship of righteous people plays a role in strengthening resolve and guiding one to the path of good.