If you work at a big organization with many exprtise reviewing your design and correcting you if you go wrong.
If you live in a country with so many experts and high standard of knowledge, all at disposal of your fingure tips.
If you work designing a project every few days, growing your experience up.
If you get paid enough for your job so that you only work one job.
If you don't have any of the above, then this forum is a great place for learning isn't it?
Mahmood