Michael,
Well to start there is no time limit on ATC exams, the length of time it takes to do the tests are different for everybody. All exams are 25 questions. If you know the material by heart tests can be finished in as quick as about 10 minutes. All ATC tests are also open book, it is not uncommon for people who are assigned tests to look for every answer in the VATUSA training material, just to make sure they have the answer right. I personally took all my tests with the VATUSA training material page open. I finished my S2 in 7 minuets and it took me 2 tries and 30 minuets each to take my C1 test. Hopefully I was able to answer your question. I wish you luck on your VATSIM endeavors here in VATUSA and look forward to seeing you on the scopes as well!
Happy Controlling.
