Thats what I'm saying. Since 2015 he's been WORKING on T'Challa. Even when he had to write him out his mind has been on T'Challa because of that. The time put in for BP1 and the BP2 up until Boseman's death is a lot of time focused on a character.
He spent 2 years post BP1 working on what T'Challa will do. Many script rewrites, etc. Thats a lot of time focused on a character. WE just dont/didnt get to see all the work behind it.