(forthose use schweser mainly) how tough EOC is ?

forthose use schweser mainly, how tough EOC is ? TO solve the EOC, do we need to read CFAI for a long-time ultimately? if the level of EOC is too high and beyond the exam level, is it better doing schweser practice exam or past exam first?? And, what your objective for doing EOC? for supplement coverage ? or prepare for high level? or both? I know doing CFAI is best, but i need advice from using mainly schweser. your advice is appreciated!!