G'day Jeremiah,
I disagree with using the pinch test at full throttle, I suggest using it only for idle mixture adjustments, to check you high speed mixture, run engine up to full speed, & lift the plane so the nose is pointing at least up at 60 degree angle, & listen to the engine, if it slows down, & begins to die, it is too LEAN, if it picks up some speed, & keeps going strong, it is set perfectly.
A very common mistake, lots of pilots make, is to have the engine at peak revs, on the ground, this is almost always, too LEAN, & as soon as the plane takes off & the engine unloads, it slows down & usually stops. As the engine unloads, it needs more fuel to sustain the higher revs, too rich is better than too lean, so try the nose up test, & check your tuning, you may be surprised.