Final answer:
Tests of controls are generally not necessary when performing tests of details of balances for expense accounts.
Step-by-step explanation:
When performing the tests of details of balances for expense accounts, the option that is generally not necessary is 3) tests of controls. Tests of controls are designed to evaluate the effectiveness of internal controls, while tests of details of balances focus on verifying the accuracy of account balances. Therefore, tests of controls are not directly relevant to testing expense account balances.