It depends on how new the pedals and cleats are.
When I got my new spd's and cleats, I backed them off, ever so slightly, so a slight twist would get me out.
I tend to lubricate mine after a few rides to make sure they don't seize up. With the wear of 4 years, I've snugged them up a bit. Now I have them set so I have to use a bit more effort to unclip.
From new, I think I backed them of 1/4 turn(maybe, can't remember for sure).