That's how they do it in Gloucestershire. One exam for seven schools. I have always thought of it as less stress. They all have slightly different pass marks and not all children ask to be considered by all schools, so each has different cohorts sitting the exam.
Yes, that's how we looked at it with the CSSE here, too (although one of the girls' grammars pulled out of the consortium a couple of years ago, so good news if you have a DD who enjoys being entered for exams, I suppose