The Dev Manager should always have this number in the back of their head. They should always be working towards it.
They see the big picture, they see how the requirements are flowing in, they see how QA is testing, they see how things are working, what is doing well, what is doing poorly, what is slowing down the team, and where they are excelling.
They should always have this number in their head + 1.
The “+1” is their own internal buffer, it could be a week, a sprint, a month – whatever metric they have, it’s “+1”. The “+1” is the Dev Manager’s level of confidence in what they need to be successful versus sliding into home plate at the last second.
And that’s why they are the Dev Manager.