Case 1 :
setWorkHours doesn't work with grouping.
check below sample. The setWorkHours method is given in dataBinding event to set the work hours for particular resource. It doesn't set.
Case 2 : (without grouping)
1. set the separate work hours for resources
2. and then set work hours using setWorkHours method for particular resource
3. The work hours will be changed based on the newly given workHours. But it wont. It is overwrites the existing work hours.