You should not do USMLE World or Kaplan or any other qbank offline for the following reasons:
- The offline qbank is outdated and companies constantly update their banks with new questions that reflect the current exam style.
- Downloading an offline qbank is considered illegal (criminal) act in the United States which is the country where you want to build your future reputation in.
- The offline version has no means of assessing your performance and it does not compare you in real-time to other qbank users.
- If you are thinking of doing offline first then purchasing the real online then the offline bank will ruin your subsequent online qbank as many concepts are repeated but in a different style and so this renders your practice invalid and redundant.
- You cannot do timed blocks in the offline qbank and this is very important to have adequate practice for the exam.
- You cannot do subject-wise questions in the offline qbank and so you miss the opportunity of hitting on your weak subjects.
- The offline version does not allow you to do a "practice mode", in other words, you have the answer and explanation below each question and this again renders your question practice invalid.
- If you say that you have to do the offline version because (you don't have the money), then the answer is that you will already spend thousands of dollars to get the USMLE done, and adding a couple of hundreds to your bill won't change the total much. It worth every penny you spend on a legal online question bank. Also there are "free" legal online banks such as the Free 150.
- If all of us started to pay for the online qbanks, these companies will flourish and they'll come up with more features that will ultimately make USMLE prep even more effective. Also, if the industry kicks off (by more people signing up) this will encourage more competition and ultimately they'll compete with each other by lowering their prices.
- The offline version lacks important features such as video explanations, timed clock, calculator, FRED software, links to resources, ..etc You will miss all of these if you do the offline bank.
- Doing the legal online question bank gives you a piece of mind and you rest assured that you are not doing something wrong and so you don't have to hide your head.
Note that this also holds true for Offline NBME, read here
NBME offline versus NBME online
Here's a list of official Step 1 question banks
and Step 2 CK question banks