why the spit turns most effectively at the limit edge and the 109 doesnt

I have to agree with Kur this time.

The elliptical form in itself had aerodynamically only most minimal to vanishing advantages above a trapezoid wing with rounded wingtips but had some advantageous side effects such as increased wing aera and reduced relative chord thickness due to the long chord lengths. That is why supermarine chose elliptical wings above trapezoid wings because these side effects provided advantages with respect to the specifications issued by the ministry.

It came at the cost of a wing very difficult to produce and it was commonly abandoned by all air forces.

If the elliptical form would have been so advantageous why did so few other air forces not adopt them? Supermarine was neither the inventor nor the patent holder of the elliptical wing.