Both but only to a small extent lol
Scanning is not the ultimate way to test if a disc will work well. Lately I find myself doing a 4x scan in cdpeed with jitter testing enabled in my Liteon LH18A1P. Then I go for a 16x scan without jitter. Usually the 16x scan will bring out more errors and show how well the disc handles at higher speeds. With large amounts of jitter, I find the 16x test elevates all PI/PIF levels.
This is why I believe CD Freaks should include jitter testing with their quality tests. Slow scanning will not show the bad effects of high jitter. I've had scans that look good but because the jitter is high, playback issues are encountered. CD Freaks would call these burns "good" or "Acceptable". Include jitter and those so called good discs look quite bad.
Your BenQ is a good example of how a drive is affected by high jitter. Scan @ 16x with your liteon and post the results here. I am interested to see how much higher the PI/PIF levels will increase.