How fast would oil drain out of a hole in the case

The gear shaft broke, caused holes in the casing, consequently there was oil starvation.
For the described problem could it be of sudden or gradual onset?
Can the car be driven if this happened gradually without notice? Could the gear be still changeabl?
What about the clutch and the flywheel can they also become faulty, and if this was not the case and both are not faulty does that help to confirm whether the process was gradual or sudden?