‎السلام عليكم ورحمة الله وبركاته ‎أحسن الله إليكم شيخنا الحبيب، لعلك بخير. How should we balance our time between new Ilm and revising older Ilm. Ex: 70% of time for new Ilm, 30% of time for revising older Ilm. Also when should we return to an old book we have completed, monthly?

There is no fixed percentage and no fixed month, one strategy is that you study through the week and revise on the weekend everything you studied, and return to a book you finished when you feel you need it. Keep in mind that when you move up to the next book in the same field you will be revising much of what you already took.