For design as such, we know that there are some advantages of outsourcing design, such as:

• the breadth of experience,
• objective opinion,
• bringing challenging perspectives for problem solving, and
• producing focused solutions.

An in-house design team advantages are:

• that they are active stakeholders in an organisation,
• focused experience,
• shared sense of purpose,
• influencing companies design culture, and
• easier access to decision-makers and power holders (Best, 2006).

Both options have disadvantages too. It is pretty clear, although the example goes from using design, that in corporate identity and brand architecture development the optimal solution will always be a combination of internal and external resources.

Source: Best, Kathryn. 2006. Design Management: Managing Design Strategy, Process and Implementation. AVA Publishing SA. 215 p.