Surely the answer to that is that it will raise the chances of scoring etc. - instead of every (I'm making these figures up) 1 in 4 it might be 1 in 2 that goes in. I also don't get what you want to know about the SA "kicking in". Surely if it's there then it will raise the chances of them being successful in that particular area but won't guarantee it every time - how would you be able to say definitively whether it had kicked in or not or whether the base probability was higher than you thought?