The answer depends on a case by case basis. Taking into account the project's length, Quality Control will automatically assign a specific timeframe for revisions. For example, contest auditions have a delivery time of 25 - 32 minutes. This time will start elapsing as soon as our team has sent the revision, and you have received the email.
Client revisions should be delivered within 24 hours after being requested. They will, however, expire after 48 hours.