in detachments--back in my day detachments were 4 or 6 people. I had both. You can respond to a non-diving incident with two (one in an emergancy) You always want someone in a safe spot that can come down and see what the big boom was all about. ANyway, one of the stories I tell in my leadership talks is about an improvised explosive device call we had. In all my objectivity I was the best IED guy on the detachment. When the call came someone else was in the rotation to go down range. As the officer, I could have changed it and went but I opted not to---I wanted to but I didn't go and sent my guy.
EOD is a life of drills--two or three a week, so the learning teaching is constant
Incidentally, I had the pleasure of having the first mixed det--male female--the beauracracy was hideous. This was a hard working competent gal and the Navy did their best to make having her live up to her potential almost impossible.