Paul was PRO for the 97 H17 Nationals in Syracuse. He used 7 as the minimum number of boat lengths between marks. I have sailed in most of the 16 nationals since then and they are also run at about 7. I worked the gate boat at the Alter Cup in Syracuse that PU was also the PRO. We used more like 10 boats as it was windy and the boats were Tigers. The spin boats need a bit more room.
Maybe something was learned at the Olympics.

How about the offset mark?
How many boats lengths away should that be and what heading from A?