If you keep your opinions to yourself, there's no one to challenge them and so your opinions won't improve.
I'm typically the type of person who keeps my opinions to myself unless asked and when I disagree with someone about how to do/build something I'll do it myself on my own time. Sometimes I'm right and sometimes I'm wrong. As much as it sucks to realize I'm wrong I do appreciate it because it means I learned something and my opinion has improved.