Yes, It is possible to crack Entrance exams without coaching and many students are making it true. What You need to do is Follow the syllabus and have good study material, Plan proper timeline and stick to it once You are done start solving Previous Years Questions and then You can crack the exam. Crash Courses can be helpful If You can follow their pace because they would be covering syllabus according to them but You understand Your need so it is Up to You if You have a proper plan then No need to go for the crash course.