Every disc I used has burned perfectly as full speed

Make sure that your DVD writer can use the 16x speed--if not you're wasting money on the higher speed discs.

I usually burn at a slower speed (8x), but even at full speed have never had anything but a superior burn, as tested with qpxtool under Linux

BTW, the better the burn in the first place, the longer the written disk will last, which is why I burn at a slower speed -- it reduces jitter.

, these blanks actually tested better at 16x than at 12x or 8x, so if your duplicator is rated at least 16x, there’s no reason to run at slower speed.

but ONLY if I use a slow burning speed