It totally depends upon the availability of the time and the aspirant's know-how of the subject.
Anyhow, it is better to follow the study plan. Read the highlighted topics in detail. When you are able to cover the topics highlighted in the Study Plan, you yourself will be able to exclude or include any other topic. It is better to view the Past Papers at that stage and include and cover the remaining topics.

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"But screw your courage to the sticking place,
And we'll not fail." _Shakespeare, 'Macbeth')