I do not think there is any magic number. Just make it look as natural as possible and do not spam! Keep the links on related pages with low outgoing links.
20-50 Approved link a day is good, Search engines like consistency in Link building a smooth graph. Let me know if you need more advise
If there quality links then you can get away with 100 a week easily. But if your spamming blogs then I would say be a bit more careful.