No they do not collect the papers for 'ALL the subejects'^^^
They are collecting papers for ATPL Flight Planning due to current problems.
CASA modified the exam due to alledged cheating, when they did, the pass rate dropped from 60% to around 5%
Ground schools have also had problems getting students to pass the CASA exam since the changes. I don't know why people have said they collect the workings for all exams, they destroy all workings with a paper shredder other than AFPA. Unfortunately pprune is notorious for wrong information.
Check out this link:
Remedy unexplained 94% fail rate of over 100 ATPL candidates Petition