I know of at least 1 organisation doing something similar to this. They have the PM of all Projects on a Timesheet Approve (or Reject) the Timesheet, but they only get 4 days after submission to do so. After 4 days, if the PMs haven't Approved/Rejected the Timesheets, they are auto-approved. I'm sure CA can provide some assistance in setting this up, with the additional step of having the Line Manager Approved the Timesheet once the PM has. This won't necessarily solve your timing problem. On the other side, I suspect you need to get some Timesheet Police established, to nag/coerce/force/cajole your people into submitting their Timesheets on time.