leading edge templates

Several years ago, we made templates along the leading edge of a
popular standard class sailplane . The particular sailplane was a
winner. It was shocking to compare the left and right wing contours
with these templated. Close? Not at all. But the sailplane went very
well.
Then we did the same on another sailplane by another manufacturer.
The templates were identical left and right. Mirror image. As made in
a machine. Perfect. This particular sailplane never did well. Not a
winner.
Conclusion?
set the flame on low,
Thanks,
GA