What do most new leaders get wrong?

They try to control the outcomes directly at a very low-level, rather than set up principles and structures so that people can make good decisions on their own that, taken together, are congruous with other decisions being made across the team. Basically, you have to find ways to scale yourself and your vision for the team without it all relying on you being present for every decision.Interview with Cap Watkins

This highlights perfectly why I often start with a UX Strategy. A great team is formed when everyone has the same goal and everyone has confidence to make decisions based on a common strategy.