I remember, many moons ago, when I was scheduled to fly a certain Mrs (now Lady) T to Brussels for a Conference, that I needed to do a Dinghy Drill to maintain currency. There was just enough time for me to complete the drill in Uxbridge swimming pool first thing in the morning and return to Northolt in time for the Task.
Cpl PTI demanded that we all complete 15 lengths of the pool before we commenced the Drill and told me that if I did not then I would be marked down as "FAIL".
I pointed out that, if the aircraft ditched, the 2 people least likely to survive were the Pilots. If we did survive and the Dinghy did not inflate and our LSJ's did not inflate then the likelyhood of our being within 15 pool lengths of the shore were minimal!!!