Seem to recall a few years (4-5) ago one particular roster lady changing rosters to stop people going into productivity and so save the company money.
For example, one guy who had successfully bid for a Manchester layover to go visit his family had it changed to a local turnaround two days before the flight. And the reason he was going into productivity was because he had agreed to do an extra flight earlier in the month.
This was back in the days when the company had enough pilots to do the job.
Guess that the reason the company now doesn't have enough pilots to do the job is a result of events like the above. Reap what you sow etc.
Said roster lady, who seemed to have a monopoly on that particular trick (maybe she was on 10%) has recently been promoted to a Flight Ops management position. Presumably a reward for her innovative rostering techniques.