How many times in a row can I take the same subject?

An applicant may take the same subject 3 times in a row (3 attempts) within 90 days of each other within a year.
For example, let's say we start the exam on 8 April 2017 for "physics" and we fail, we will have until 7 April 2018 another 2 attempts to pass "physics", separated by at least 90 days.