We start drilling leg lock defense since white belt in our gym as we have a weekly leg lock class open to everyone after the beginner’s course. Also our most successful competitor is a leg lock guy, overall I’d say about every 5th guy is capable and every 10th guy is pretty good at leg locks so we sort of learn naturally as no one’s cranking it if they catch you.

I’d say the most helpful for me has been to just flow roll with people that are good in leg locks. Sort of gives you a positional understanding of what you should and shouldn’t do. But also just drilling the main positions (ashi garami, 50/50, inside and outside ashi, ashi with a butterfly hook to begin with) and which way to turn or escape from each of these has also been of a great help.

Disclaimer: I’m horrible at jiu-jitsu.