Coming from a military background (RAF) I became used to the planning then briefing system following a format.This carried over to my sub aqua dive supervisor off duty exped and training times. Looking back at what went well and where we had an incident the service system coped by making you think about contingency. By contrast I have taken part in marine and aviation activity ” organised” by others. The make it up as you go along process seemed the most common approach. Those with self confidence and ability to clearly be in charge had a good system in place. The lesson to be learned is to allow yourself and the team enough time before the activity to make a plan, do the checks, make the briefing.