The best practices for policies are listed here.
Use policies sparingly
Try to keep a few different policies and apply policies on groups of objects. Meanwhile, it is possible to apply any policy to a concrete object.
Clone policies to edit and make changes
If it is necessary to edit or change some of the content (metrics, alerts, and capacity settings), it is recommended to use a distinguished policy (can be even a currently active policy) before making or applying any change.
Do NOT change or edit the default policy
At any time, do not directly edit or change the default policy, as it has an impact on all existing objects