depends on where you're at. how long has it been since you took the last one? have you had enough time to work on the deficiencies it showed? or are you more worried about pacing and test-taking strategy at this point?
the only thing NBMEs are good at is showing you your weaknesses. it's best to think of them that way first and as predictors a distant second. that way your study is driven by process, as opposed to outcome.