Here is an interesting lecture from an ex-Blizzard and now one of the managers at Riot games (League of Legends).
Assuming designers fail as much as any other professional (and it doesn't matter if they're senior or not) he encourages to share design work and ask for feedback as soon as possible to avoid those mistakes.
From my experience in the Spanish industry this doesn't work here. Early works are rarely judged as they are, and most of the time they're critizised to personal gain, or simply analized with low constructivity. I'd love to work on an environment as he describes, though.