Timzsta
The dayoff payments are very rarely used in my airline.
Their main purpose is to concentrate a crewing officers mind to find an efficient way of solving a problem rather than the way that is easiest for him and, therefore, could result in many pilot's rosters being changed ie. to cover one duty he shifts around half a dozen pilot's duties!
It is good way of making sure that as a (future) pilot you have a stable roster. Something that you will come to appreciate in the future.
The company very rarely pays out for day off duties unless of course they have completely cocked up their crewing levels. It is also down to the pilot if he chooses to work a day off. It , generally, works very well.
PS I am ex KLMuk as well and pleased that I got out when I did. Give me my present company over KLM any day.