There is a bonus system that encourages trades people to work longer hours. There is a system that gives bonus hours so that new skills can be learned more quickly, and a wage scale that goes up as a function of the number of hours worked.
When construction workers have their plate full with work that needs to be done, they give it all they have got in order to improve their employment conditions. The notion of work-sharing has become difficult to pin down in their context. The bonus system needs to be re-designed.