CRMI's had the facility to bid for a 5 day off string removed many years ago. Their only concession, as TU highlights, is the requested flight. Many of them, particularly those on the 330/777 will have night turns even in their top bid months due to training duties being pre allocated before they get the chance to use the CRS bid. With duties spread out, this does not afford efficient rosters so turnrounds are inserted to to achieve maximum productivity.
The new system should reduce this discrepancy......apparently.
Harry