Shapiro's pivotal study showed that even dedicated, long-term meditators started practicing for self-regulation - to manage stress. Shapiro showed that with continued practice, a gradual shift occurred in the intention behind practicing - from self-regulation, to self-exploration, and finally self-liberation. Critics of Jon Kabat-Zinn's MBSR would do well to read this paper. Shapiro DH. A preliminary study of long-term meditators: Goals, effects, religious orientation, cognitions. Journal of Transpersonal Psychology 1992; 24(1): 23-39.
The realization of the existence of sickness, aging, constant change & death - managing the stress of existential angst - initiated Gautama's journey. He did not start with self-discovery or self-transcendence - he first tried materialism (clinging), and when that failed, he tried the other extreme, asceticism (aversion).
Today, "relatively few arrive at Buddhist centers on the wings of psychic victory. Many people have a psychologically complex history, one influenced by trauma or loss. In this way, we practice to resolve thorny and entrenched forms of psychological pain." Pilar Jennings PhD "Looking into the eyes of a master. A relational psychotherapist explores how we can see our teachers as people, both gifted and flawed." Tricycle Spring 2004
In our youth (not strictly in years), we can read, hear about & observe adulthood, yet no matter how "smart" we may be, we simply cannot rapidly integrate mature psycho-social-spiritual concepts into our immature being.
Earthly existence seems to entail direct personal multi-dimensional experiential iterative learning. Intellectual bypassing does not bring about true maturation any better than daydreaming. Yet neither is the process perfectly linear, mechanically step-wise, nor predictably dose-dependent (hours on the cushion).