Yep, that is basicly the point. With some tight engines it can take 10 liters before the pinch is gone and with others the pinch is gone after 2 tanks. Both situations do not give an optimum fit of the piston/sleeve and so no maximum performance.

I do not think matching is done, that is from the old days. With current machines it is possible to enter some numbers of the sleeve in the program and take out a piston with almost a perfect match. I know this because my sponsor can do this.