It extends as society gets more complex. Identity vs. Role confusion. Establish philosophy of life. Adolescents think in terms of ideals. Problem is that they don't have much experience.
Adolescents tend to substitute ideals for experience.
Ideals are different from reality because they are conflict free. Extremely rigid, unbinding set of ideal - cults, or merely totally dropping out. Work is now crucial. Spend most of life preparing for this stage, end of life recovering from it. Rejectivity - don't care for specific groups.