This is difficult question and answer can be tricky. Most of the time exam pattern gives its answer. Lets consider different cases
1) Suppose exam is an objective question with 100 or 150 questions to be answered in three hours then expectation is that examinee had covered whole syllabus though very deep knowledge may not be mandatory. Such examinations expect that you are clear in basics you are aware of important examples, you can use formula of the topics properly. In such tests you don’t have much time to invest on individual question. Normally such tests have negative marking too, to test “correct in first attempt” aspect of your personality. Trends of personality tested in such tests are normally:
a. You are hard worker and cover whole syllabus in time
b. You can remember what you learn(memory recall) and apply them in short span of time
c. You properly plan your time and know how to get best in this short time
d. You do not commit mistakes in calculations, short but quick calculations tests you
e. You are a good reader, many a times answers are hidden in questions and a small mistake can do blunders for you
f. In such tests a small mistake can make you in or out
2) Another type of objective test is where say 50 or 75 questions need to be answered in 3 hours. Though this is also objective test but it is searching candidates with different qualities. Such tests give more time per question and hence questions are not straight forward. They test more on application of your knowledge. Formula is same but you have to apply different tricks and may need to break the problem to apply the formula’s. Such test requires deep understanding of the subject. Coverage of whole syllabus may not be necessary but deep knowledge and presence of mind is necessary.
3) Let’s look at subjective tests. These are completely different type of tests and check different aptitude of the examinee. They check deep knowledge of user in the subject along with capability apply knowledge in numerical questions. Proper presentation, restrict to word limits and proper answers are expected in such tests. Normally such tests also give options among questions. In such tests covering whole syllabus is not necessary but deep knowledge and good practice of numerical is necessary. In many cases comparison of stats, examples etc should be remembered and quoted in the answer.