Probably not the information you want, but ...
I had a friend stay over quite a number of years back. He was a KLM 747 FO and he was looking over my shoulder at the features of our CRS bid system in wild wonder. His rostering rules were:
-ONE requested flight per YEAR
-swaps not permitted
-only the first two weeks of any month's roster were considered to be firm, the remaining two were considered to be 'TBA'
Be careful what you wish for.