When testing a mission critical system a high coverage should be achieved.

Multiple condition coverage is a structure-based test technique that aims to achieve a high level of coverage by testing all possible combinations of conditions and outcomes in each decision point of the code or design of the system under test. Multiple condition coverage verifies that each condition in a decision point has an effect on the outcome and that there are no hidden defects or logical errors in the code or design. Multiple condition coverage requires some knowledge of the internal structure or implementation of the system under test; it focuses on how the system does what it does rather than what it does. Multiple condition coverage is one of the most rigorous and complex structure-based test techniques because it can generate a large number of test cases for each decision point, especially if there are many conditions involved. You can find more information about multiple condition coverage in [A Study Guide to the ISTQB® Foundation Level 2018 Syllabus], Chapter 4, Section 4.3.