Correct me if I'm wrong but the top skippers (say Figueroa) in the H16 class
go up and down wind with with one rudder? (req's practice)

Try sheeting in & out the main on a H16, and measure how much the rudder toe in changes?
(on some boats its more than an 1/8")

Vs the Tornado (a very STIFF boat) use both rudders.