Governance
Picking your battles means that you focus on the important things: on the result. Think, for example, about tying shoes. You have been taught to tie your shoes one way, your spouse has been taught another way. Both ways work equally well: neither of you trip over your shoes, the ties look the same and they don't get loose during the day. So the way your spouse ties his or her shoes, has no impact on the result; it is just a matter of habit and taste.
The same applies to activities within your organization. The way you implement a service has to adhere to certain rules to ensure quality. But within these guidelines it doesn't concern anybody, except the team. Picking your battles is important for several reasons:
You can't control every project or activity in your organization in detail; large organizations have a lot of projects and changes. It is important to focus on guidelines and the result, and not waste time and energy on minor things.
Change takes time and certain preconditions...