Resync cost price on timesheet line
It may happen that mistakes are made when setting the cost of an employee. The company.employee_cost_price table keep the history of this cost. So when the cost is corrected/modified, it may be good to have a wizard that re-synchronize (calling sync_cost) on a set of lines (probably based on date range).
For that it may be good to improve the sync_cost code to group write per cost_price.