It depends on the person. Not everyone needs code review to strive for better and know when you're doing poorly. Collaboration is an easy way to get that, but

It depends on the person. Not everyone needs code review to strive for better and know when you're doing poorly. Collaboration is an easy way to get that, but it's not required. The same people that have the personality to learn things on their own often are the same that will improve their code over time without someone else.