As far as activation goes, I spend at least 25 minutes every day activating. "Successful activation" feels like different things, depending on what happens. For example, I was using "The Tinitus Handbook" as "a book" for my PhotoReading 5-7 books a day (to spur spontanious activation). When I actually got around to doing a Preview for it, I noticed I was super-reading and getting everything from it while I was looking for bold text. I stopped doing the "preview" and went right into manual activation. Other books, I get a "I know what he was thinking" experience with the author, where you get the higher-level thought the author was putting into a book, because he had to explain his wordless thoughts with words. Mindmapping helps activation the most, because it "locks in" what you know into another form. Also, you know you have had a successful activation if you can answer your mind-probe questions. For example, with the Tinitus handbook, I put the book down, went to the kitchen, turned on the faucet and put my ear next to it. This action let me know "Will a masker work for me?"

As far as knowing if an activation session is going to be successful, one of the clues I have is understanding the book's structure and layout on an intuitive level. Previewing helps, of course. For example, "Turn to chapter 10," you can open a book and be pretty close to the start of chapter 10.

For spontanious activation, it helps sometimes to just B.S. Yes, actually say things that you have absolutely no support or evidence for. Whenever I do this with a book I haven't had the time to manually activate, I can usually turn to the right page in the book to support what I'm saying. I wouldn't recommend this for exams, though.