Distiller behaviour

When any body use Distiller to convert Postscript file to PDF (for example file  qwer.ps)

Distiller has two ways to create PDF

1- Create tmp file with tmp name and starts write the contents of the PDF to it and after finish it rename the file to qwer.pdf

2- Distiller creates directly qwer.pdf and start writing the contents (the qwer.pdf was locked for writing to other apps)

after distiller finishes writing the PDF it frees the  qwer.pdf.

The question

Any body know when Distiller will use  method 1 or 2 !?   and how we can control/force distiller to use 1 only or 2 only !!

It is not the memory size because distiller still do that on any PC with large memory and it still use #1   even with small postscript file !!

Regards

Adam