Your presumption is correct. I passed in April.
I bought the ‘powerhouses’ and never found a use for them. Lagrega was completely useless. The sampling one was less than useless. And I never used Cooper/Alley during the exam.
I dont know why my experience was so different than the rest of the posters. Maybe it was my background, the particular exam I took, or a combination of the two?
Good luck in the exam. Relax, take your time, focus on what the questions are asking, find the tricks, and most importantly: get the easy ones correct!!
I used Davis/Cromwell quite a bit in conjunction with EERM. I found some of the approaches in the solutions in Davis/Cromwell to be easier for me to follow. I also found some of the equations solving for the same thing were presented in a better format in Davis/Cornwell vs. EERM (e.g, easier unit conversions, etc.). When I found those I made a note in each book on the corresponding equation telling me which version was easier for me to work.