Jennifer,
I followed the first 3 steps on every book. I only activated 1-2 books/week. It's interesting that, although I may not have a conscious awareness of much of a book, I know after the PR step whether or not I want to activate. There is a feeling there that I don't need to do anything else. I drop those books and pursue them no further.
When I do activate, I tend to do it at least a day after the PR step (sometimes it's several days if things get busy).
The timing issue was a big one for me. I spent too much time doing everything. When I first started, I would spend an hour or more doing the first three steps. Paul is very clear in the homestudy course that you should stick to his time schedule. When I did, the results improved (and so did my satisfaction with the process--I hated PhotoReading when I was allowing that step to take 30 minutes for a book). Now, I try to spend around 5 minutes on prepare/preview and 5-10 minutes PhotoReading (depending on the book).
I recommend the 5 day plan. My first experience was not at all impressive but I realized afterward that I wasn't being true to the PR steps. The second experience was great. I followed all the steps explicitly and got a great deal out of a book with less than 2 hour's effort over 5 days. This second attempt was what really got me excited.
Another thing I did that was a mistake, was trying to activate a book by mindmapping the whole thing (Chapter 1, Chapter 2, Chapter 3...). With the second attempt at the 5-day plan, I mindmapped based on my trigger words. I mindmapped concepts, rather than book structure. It made a big difference.