Regarding awarding high rank at young ages, here's something I posted on an earlier thread.
In the system I began in, my sensei had been promoted by Kuniba to 5th dan at age 34 with only 16 years training.
There has been some mention of the dan factories that have existed in Okinawa for the Marines and Airmen stationed there. From my U.S. location, it is hard to differentiate a dan factory from a legitimate traditional Okinawan Karate dojo. But following is an example of a mainstream Okinawan system awarding high rank to a rather young U.S. airman.
On
http://www.usashorinryu.org/About/fdrh.cfm, Frank Hargrove describes his ascent under Shuguro Nakazato. After a year he made shodan, and three years later, at the age of 22, he was promoted to 4th dan. Six years later, he was awarded 6th dan.
My guess as that Hargrove was in the dojo pretty much every waking minute he was not on duty, training many hours every day. But even so, his blistering movement through the ranks is an indicator that this issue of rapid promotion is not limited to U.S. dojos, but can been found in mainstream Okinawan schools as well.