I was brushing up on my principle parts for a quiz and came across this salient counsel from David Alan Black. This is especially sage advise to my friends who are using the Keyword Study Bible
You must, however, keep in mind that interpretations that lean to heavily on subtle nuances of Greek verbs are seldom worth considering. For instance, it is all to easy to “over-exeget” verbal aspect. “Do not believe every spirit” (1 John 4:1) uses an imperative of prohibition in the present tense. Does this imply that John wants his reader to stop being deceived? Possibly, but this grammatical construction doesn’t always forbid an action in progress. Once again, it is in the context, and the context alone, that is determinative.
Your challenge is to use your understanding of Greek verbs as one part of your ongoing study of the most important book in the world. And you will enhance your ministry if you wear this knowledge with grace and humility.