I refused for lvl I and now for lvl II to do mock early and get carried away with it because even by doing 5 or more mocks you can be certain you wont be tested on the entire curriculum.
I usually study the entire curriculum doing EOC and then review once doing EOC again and finally reviewing an entire subject at a time (i.e., Ethics or Econ) and then doing all the EOC for this specific subject (I repeat EOC this time because I do not use a Qbank prep). This gives me a better chance to have covered everythimng multiple time and EOC usually try to cover everything with at least one question.
Finally I dont think you should not do mock this is not what i am saying but they are not what prepare you to do great at the exam. To me they are just a confidence booster or buster and let you know where you stand (with a huge standard deviation though due to the small amount they cover). They alos however can be good at spotting specific weaknesses but again if you have done multiple times EOC or chapters questions blue boxes you probably already have figured out these weaknesses.
I am planning on taking 3 mocks and maybe a sample exam from CFA website but focus will be on mastering and covering the material not on doing well in 120 questions out of 1million possible