How perfect ?
A plane doesn't have to be perfect to fly. It does need to be structurally sound, balanced properly, control throws and directions correct and generally in alignment. I have seen some pretty ugly planes fly. One club member's wife named his trainer the "ugly duckling" and it was a lot uglier than it sounds. Once in the air it was a thing of beauty and had over 300 flights until an attempt was made at an outside loop. He said "if the soybeans had been harvested I would have made it". This plane had been crashed twice before being used by this member to learn to fly.
EXCAP232