Even if you are a strong designer or developer yourself, as a manager you will achieve way more by multiplying the effort of your team than adding your own contribution to it.
Multiply your team by instituting more effective processes, enhancing team skills through training, or adding new team members.
As great as you are, one person will never beat a team of people firing on all cylinders.
Your role as a manager is not to do the work yourself, even if you are the best at it, because that will only take you so far. Your role is to improve the purpose, people, and process of your team to get as high a multiplier effect on your collective outcome as you can.
Often multiplying team efforts requires a long timescale to see results. If you are under short term pressures you may need to prioritize meeting those demands, potentially by adding your effort to the team.
Julie Zhou, The Making of a Manager