Revision is an essential aspect of AIIMS, so one should do it as many times as possible. It does not matter how many times you revise the syllabus. What matters is you revise the entire syllabus from start to end to freshen up all the concepts of the whole syllabus in a short flash. Each revision should be complete without missing or skipping any topic. Instead of receiving the syllabus repeatedly, again and again, sit down, relax, and precise the complete syllabus in one go.