Someone giving work like that should be either junior enough that there is potential for training them, so your time investment is worth it, or managed out. Or

Someone giving work like that should be either junior enough that there is potential for training them, so your time investment is worth it, or managed out. Or it didn't really matter that the function was complex if the structure of what's surrounding it was robust and testable; just let it be a refactor or bug ticket later.