It's a normal problem during such kind of exam which contains a vast syllabus with varieties of concepts.Don't hype this issue in your mind.Try to develop several strategies like kind of experiments , contain one in your pocket , which suits you most.
You must move with deadline for subjects.make a hierarchic schedule which follows kind of top down approach like rough plan for next 3 months then divide it into month by month with more clarity and again subdivide it into as per week wise or 10 days wise , here when it's just 7 days , your focus would be much better. Set deadline for subjects like for OS 4 days are enough to revise (1 day for basics , 1 day for process thread deadlock , 1 for synchronization ,1 for mem mang )(4 day is general case , if you have good enough knowledge , you may take only 1-2 days).
it may happen that you may feel unsatisfied even after 4 days , but it's okay you have to prepare schedule in such a manner that at least 2-3 times you can face revision. if you can efficiently study one subject whole day , it's okay otherwise you may study 2 subjects in a day.
Don't get emotional during revision in that way you'll spend more day than planned. it's hard to do exam oriented study , i face same problem. i have spent more than months in just studying one subject and this made me bad with exams.
eventually you have to develop your own technique for revision.develop ideas for this and implement.don't leave revision for last months , you will be in better position if you start it now.strict to the schedule you prepared for yourself. it's a good approach to keep revision and mock test in parallel.you can allocate 1 day just to analyze and bind up your revised subject , after covering it. or you can do it after covering pair of subjects or some other way as per your what suits you.