I think making mistakes and discovering them for yourself is of great value, but to have someone else to point out your mistakes is a shortcut of the process.
But one of the things I learned is that when you fight for something you believe in and you tell the truth and you do your best, you can always hold your head up high and no one can take that away from you.
If I was a fashion designer just following trends or designing for celebrities, I would not be fulfilled.