How long should you keep your arm in a sling after broken upper arm?

Normally 6 or7 weeks, however, I had a very large tear in mine, that involved both infraspinatus and supraspinatus tendons, which were both completely detached. He extended the "standard" by 3 weeks to reduce the risk of re-tear in my case. (this is because there was no intact tendon portion to help protect the re-attachment.) A re-tear is a major disaster from what I hear, so I'd comply with the doctors plan for sure.