I can confirm that some of today's older bigshots who grew up as a jw in the fifties and sixties were given responsibilities way beyond their years due to a lack of brothers - and this in a city of half a million population and a few congregations even then.
We certainly had a 16 year old give his first public talk, a 17 year old Assistant Ministerial Servant (as they were called in Qualified to be Ministers in 1967) taking a group study with a 50 year old doily wearing sister as his assistant - and even when the elder arrangement started in 1972 and there were plenty of brothers we had a 22/23 year old elder appointed.