book 6 vs. sample exams

for those of you who have done both kindly advise: which is better: an exam from book 6 or the cfai sample exams?

To guage where you are in your prep: CFAI mock To use as a study guide and review tool: Schweser book 6

I am doing Book 6 and the CFAI. Skipping book 7. Got to do the CFAI sample, i feel like its kinda must.