When I design a residence, I do not have to consult other except for the structural designer.
Almost whom I consult is a craftsman, because of asking them about the making method in the site.
When I design, I almost decide the way of the structure and the joint design and the size of every wood beam by my self.
Just as I will design also for electrical work and plumbing work.
After that engineers give me some advice, I seek a solution many times, leading to a final plan.
So if you want to do high perfection design, you need to know a specialized knowledge that what is possible and what is impossible.
If you have a specialized knowledge, it will increase the freedom of design.