Roughly, each activation pass, should be no more than 20 minutes each. Use a timer so that you do not go over the alloted time. After 20 minutes, "Take A Break"!!!! Get away from the book or material. Drink some water, play a video game, take your mind off the book. Come back later and activate the book again for your 2nd pass thru the material/book. Spent no more than 20 minutes for that session.
