As designing test cases is quite important activity of testing phase , does not matter what approach we are using that is traditional waterfall or agile.
Do not throw test cases until the program life has ended, when we create test cases to test a specific functionality of a module, effort is there to create test cases to cater all scenarios. But after testing if the test cases are thrown away, it would create difficulty when we have to re-test the program it mean the effort we put for creating test cases will be lost so maintaining the repository of test cases is a good practice.
Having test case repositor helps a lot when we are going to automate regression testing as well.
7 hours ago