Wouldn't practicing racecraft include putting yourself in tight situations and learning to drive close to someone without touching. For me, i purposely put myself in uncomfortable situations on Thursday such as getting side by side with someone through a tight part of the track to get experience dealing with that situation and not panicking and lighting up the rears. Doing this results in accidents of course at times but come Sunday i am more prepared to race competently when things get sketchy. And it has worked well, i would say i am among the least penalized drivers in snail history and i would directly attribute it to finding the limit through practice.
Also, if it's just practice then who cares if you get taken out. No one tracks practice night results. I get taken out in practice sometimes, its no big deal theres nothing at stake. Just get back going and keep practicing. I am sure the people who cause the accidents are learning valuable things about how to avoid trouble on sunday and that is worth something.