I guess there are different approaches to postviewing.
I agree with Alex that after you have a few questions it is a good idea to check if they are aligned with your purpose and if you even need to recheck your purpose. The key thing to my understanding is, though, that you continue postviewing as long as I get a general understanding of the structure and then start with my questions and activate section(s) that help most.
For me it might be - since I write down questions as I go - that the really juicy questions actually are not among the first few. And since the questions really build up the excitement and hunger, I tend to pull more. The extra time spent is really nothing compared to the gain.
Also, it is quite difficult to say an exact number of questions or trigger words to pull - it depends on the material, your needs and purpose.
Sakke
