In mainstream practices, it is one party that designs a house, another party which builds. It leads to all sorts of problems. The architects design things that cannot easily be built or be easily built another way and the builders complain. The design is legally binding. The architect has already considered the project over with. Changes are very expensive.
It makes much more sense to have more of a seamless flow where design and implementation move forward hand in hand with feedback from one step to the next.
It requires putting together a different sort of team and working with different sorts of contracts that support and protect all parties. It works beautifully, no wasted time and funds on backtracking.