I've recently been to Siwa as part of a charity caravan managed by volunteers from Resala. The aid caravan consisted of 245 volunteers. The caravan lasted for four days and nights.
The caravan was headed by one volunteer who had a number of assistants. Each of the 7 busses had a leader. Each of the several hotels in which the volunteers were accommodated also had a leader from among the volunteers.
The interesting thing is that such volunteer leaders had not received any kind of training in how to manage other volunteers, how to organize or any kind of leadership training to prepare them for shouldering such responsibilities. There only credentials were participating in previous caravans with Resala even as regular volunteers.
One of the volunteers who was with me in the bus, but was not the leader of the bus, was a regular volunteer until he was assigned to become the leader of the hotel in which I was staying. He was younger than me, a college student still. He was responsible for collecting our national IDs, communicating with the hotel front office staff, waking us up at times of prayers, meals (Iftar and Sohour since it was Ramadan) and work (our volunteering work, the main aim of the caravan). He was also responsible for handling any issues that came up and managing the flow of volunteers in the hotel he was assigned to manage.
I observed this 'regular' volunteer shoulder his new responsibilities and become gradually more capable of handling them. By the end of the 4-day caravan he was acting like a capable manager handling things with confidence. It was like a practical hand-on leadership crash course.
A second observation I had was on our way back from Siwa. The other volunteer who was responsible for the bus I was in on our way to Siwa was also responsible for the same bus on our way back. I was not in close contact with him, except in brief occasions, during the actual days of the caravan, for he stayed at a different hotel. On our way back, I noticed a dramatic positive change in the way he was handling the bus and dealing with volunteers. He behaved is a highly confident experienced leader as if he had been through many years of leadership experience. The observation was so clear to me that I marveled at how a few condensed hands-on throw-me-in-the-water kind of 'training' would produce such amazing results that many an expensive leadership workshop cannot even get near.
I am not saying that formal training, workshops and regular training sessions are useless, indeed they could act as a good start to introduce new would-be leaders to the necessary skills they would need when they are assigned with their new responsibilities. Yet there is no equal in terms of the strength of the effect nor the briefness of time to learning by actually doing. I see Resala, the volunteer organization handling the caravan, as leadership incubator in which regular volunteers enter and become veteran leaders in so short a time and without any kind of formal training.