People train to be parents? People train to go to school? Those struck me as funny. Training for school and for parenting are both typically OJT. Those two aside, the analogy doesn't completely make sense. What do all of those people have in common? They do the thing they're learning. They play music... lots of it. They teach classes. Tons of them. They log countless hours driving cars and actually track the number of hours they spend flying planes. They cook food that they will eat just about every day, and they actually create drawings. What does a typical self defens...er do? I understand your point, that there are things that have a steeper and more protracted learning curve. But a cook doesn't get better as a cook unless he/she cooks. A pilot doesn't actually get better as a pilot unless he/she flies a plane.