> Very few people are promoted to a senior role already knowing how to manage a team well or how to balance requirements.

There’s more to it than that. If you’ve had a chance to work under someone who knows how to do the job (or someone who doesn’t, but you can see other groups that work well) then you have some idea how to do the job.

It’s similar to programming, or any other job: you write good code and bad, and learn which causes more problems; you read good code and bad and learn from it which of your own practices are good and which are not.

You don’t understand what was in your textbook until you see it in the real world. All that takes time.