Not many classes reach a point where they need to split the fleet. The Lasers do, but they can still have over 100 boats on the start line.

Most classes (if not all) have much smaller numbers than they had 20 years ago, and back in the 70s and 80s it would not be unusual to have 100 boats on a start line. That's one reason why gate starts were used a lot more in those days.

We have been a bit spoilt over the last 10 years with plenty of room on the start line. If the starts get too crowded then the line can be made longer - up to a point.