Wrong grouping for Hours per Work
The view 'work_graph' uses "name" for the X axis.
So this means that the durations of works with the same name will be grouped. I don't think it is what is expected.
I think the solution will be to use a for the X axis a Many2One that points to the record like that it will be grouped by "id" which is unique and it will show the "rec_name" of the work.