I don't think the length of the stroke has much to do with irritation or leaving stubble behind. I use both long and short strokes depending what part of my visage I am working on.

Irritation has a few causes, poor edge, poor lather, too much pressure, wrong angle or a combination of those things.

If you are trying to remove all your stubble in a single pass you are likely using too much pressure for sure. Multi pass shaving gradually reduces to stubble pass by pass. The number of passes used is whatever gets you the shave you want in "comfort" and varies with the individual. Some find that 1 pass does it for them and others use up to 4 passes.

Bob