If you’re planning to study 3000/4000 words for IBA MBA preparation, that’s okay. Learning new words was fun to me & I think it’s always good not to keep any loose end in your preparation. But the point here is, in case of IBA, being intellectual and brilliant is less important. What’s more important is being strategic and smart. Suppose, you’re planning to study 4000 words and in the mid way of your preparation, somehow you lost your interest due to some unavoidable reasons. What will happen then? Suddenly you’ll find yourself just a month away from the admission test with piles of unknown words remaining in front of you. That won’t be smart, will it?
Thus, again, The Priority Setting Theory comes to play. What do we do when we perform Salah? Our first priority is Fard Salah because it’s compulsory. Only after that, we think of Wajib, Sunnah or Nafl Salah. Just like that, when you’re learning vocabulary, you have to learn the compulsory words first. The number of these compulsory words is not more than 1500. There are Wordsmart 1 & 2, SAT 1000/1500 words etc books. I’d prefer Wordsmart. Finish learning these words first. Only after finishing these, you can think of learning more words if you have time for that.
If you analyze the question pattern of last 2-3 intakes in IBA MBA, you’ll see that vocabs based questions were few in numbers as IBA is emphasizing more on grammar based questions which evaluates your natural language skill. Keep that in mind.
Be strategic. Be smart.