One of the most important parts of the job of an engineering leader is assembling a team of developers that can work together in the most efficient way possible.
The selection of your team members might be influenced by capabilities, personality, and seniority. When thinking about seniority, natural questions arise on how many senior members is too many, how effectively a junior engineer would be able to address complex technical challenges, or if hiring graduates would boost creativity.
One might assume that if you have a completely free hand in picking your crew, then you just go for the best and most senior engineers you can get.