Should all test cases be reusable and in the test suite? or are there scenario's where you would want to create a specific test case for a single user story? (or a combination of both)

i.e. a bug was solved for a specific OS. In this case I would actually like to test that specific OS and maybe one extra OS and focus mostly on the bug testing. Should you use a generic test that covers way more scenarios or could you just copy/create a test for this specific user story and use this as a throw-away functional test?

Other scenarios I could imagine are i.e. partial functionality or single time edge cases.

I tried googling for answers, if anyone could give me a source as to how this would work, that would be great.

Should all test cases be reusable and in the test suite? Or are there scenarios where you would want to create a specific test case for a single user story? (or a combination of both)

e.g. a bug was solved for a specific OS. In this case I would actually like to test that specific OS and maybe one extra OS and focus mostly on the bug testing. Should you use a generic test that covers way more scenarios or could you just copy/create a test for this specific user story and use this as a throw-away functional test?

Other scenarios I could imagine are partial functionality or single time edge cases.

I tried googling for answers, if anyone could give me a source as to how this would work, that would be great.