The requirement is that you have to be supervised by an unrestricted FI(A).
How this supervision is administered is largely left up to interpretation. I've taught at schools where your supervising instructor would sit in on a number of your briefs, and even back seat occasional flights, right down to other schools where someone could be "supervising" you from home, while you're the only instructor at the airfield.
Each school should have their own policy in place, and this should hopefully be clear in their flying order book.