Haven’t done a single CFAI EOC, passed 1 and 2 first tries on the Big S only. Echo the sentiment, depends on the person. If you have a solid finance background, work as analyst, or been on trading for a few years..EOC’s will likely become less important. If you have less front office experience, it might become more important to do the EOC’s.
This is not to discount job functions, or bash anyone. but in the frontoffice, depending on the role, you are more likely to have expertise that crosses into some of the larger/harder sections. Like Derivs.