When I would send guys down to Tex to do guest stars I would warn them to "add 3" to whatever the stunt coordinator said was camera acceptable. 3 Inches distance. I fought competitively for 8 years, I don't remember ever (either a sub or a strike) really doing serious damage to a training partner. However, I have misjudged a person's blood alcohol when choking them and put someone to sleep I didn't intend to. Lawn Jiu jitsu always ends poorly.