If I have 16x speed DVDs and I burn them at 12x or 8x speed, does this help assure the data burnt to the disc will not have errors/flaws?
Actually, yes. Faster a disk is burnt, higher is the chance the media may not have recorded it, and consequently higher is the chance of errors, especially with low/cheaper quality media. More detailed explanation here.
The optical media has a lot of error correction.
Burning at fast speeds is said to introduce errors (there is a probability based on environment conditions).
However, most people at CDFreaks seem to suggest that is not really required.
I have usually done writes at full speed (matching the media limits) for data.
For, audio writes, I am a bit skeptical on the theories and slow down a little for safety.
Yet, have not confirmed burning faster would have been a problem yet.
I have a feeling that these audio speed reductions were useful in the earlier days when media, writers and specifically the audio-cd players were not quite up to mark with the optical media handling.