NOMTW - I strongly disagree with your first premise. Getting a second opinion is very important, and does not show a lack of maturity. Farkert, it shows maturity in that you are willing to take into consideration the advice of others and that you don't arrogantly look at yourself as an expert on everything.
There is a Torah shmooze on Nadav & Avihu, the sons of Aaron, that states that if they had consulted with each other before bringing in the aish zara they wouldn't have went through with it, and their lives would have been spared. It's interesting because they both did the exact same action, and they did it together. You wouldn't think that simply speaking out what they were doing to one another would have made a difference, but chaz"al teach us that it would have made all the difference.