Honestly, I don't train at this point to defend myself. I believe SD is very much based on mindset, experience, soft skills, and physicality, then gross skills that don't go away behind those, and the technical skills in a distant sixth.You can maintain it for a while by shadow kicking randomly, but it reaches a point eventually where the leg muscles just aren't there anymore and you either lose power or form or both. Getting back is fast but not fast enough to defend yourself. You don't have kick trials in a self defense situation, were you to ever need it
I'm confident in my experience, I've forged the soft skills under fire, and like @jobo said, the gross skills are pretty much there at this point. My side kick might get sloppy but it'll still work, for instance. So the training I do at this point is for enjoyment more than anything else. If my goal was SD, my main focus should be on strength training and sprinting.