Aspects of the invention include determining a functional coverage model for a system under test (SUT), the functional coverage model comprising a plurality of attributes, wherein each attribute includes a set of values, determining a set of test cases having n-wise test coverage for the SUT, executing one or more test cases to determine an execution bottleneck value in a first set of values for a first attribute, analyzing the set of test cases to determine a first test case having the execution bottleneck value for the first attribute, the execution bottleneck value having a larger execution metric than a second value, determining that the first set of values for the first attribute in the first test case is moot for the n-wise test coverage for the SUT, and replacing the execution bottleneck value for the first attribute in the first test case with the second value.