Most CD & DVD burners made in the past 3 years are able to test the CD
being
burned, to determine good workable burning parameters for that particular
disc. Burning speed and other parameters are adjusted accordingly.

Yep which brings something more I have to say that is totally unrelated to
audio but nonetheless in context with the thread.

Since a CD-R is write once how is it possible to test the recording
parameters without actually recording on the disc? If the software does lay
down some form of 'reference' data to the disc how then can the disc be
'overwritten' ?

The success of these operations varies with the quality of implementation.

Do you mean the hardware and software used or more inline with the knowledge
of the user?

Steve