Given that we have set of test cases, we would like then them to be effective. What does “effective” mean? Effectiveness of test cases is the ability of the test cases to be able to detect (or uncover) the defects that can affect the customer experience. So a clear understanding of what *types of defects* are we looking for and a mapping of the test cases to these test cases would enable a scientific way of assessing effectiveness.
What is efficiency? It is ensuring that we execute the test cases in as short a time as possible with optimal effort and no more. Understanding (1) the priority or business importance of test cases, (2) knowing what test cases to execute in what part of the lifecycle (3) clear segregation of test cases by various types of tests and levels enables to optimize testing and become efficient.