By not waiting for a subcontractor to come to your shop, you can have better control of your workflow and have your staff working on the vehicle sooner.  Some customers choose to remove the glass themselves, and call the glass company for reinstallation.

Has the subcontractor ever damaged the vehicle or scratched the paint during removal, causing you more unnecessary work and cost? 

Consider how many jobs you sub out per month.  You can improve your income by invoicing labor to the customer/insurance company rather than having an expense to pay to the subcontractor.  Now project the savings over one year.