Billed Hours, Then Car Count. The right order of analysis

Across the country everyone talks about needing more car count in their business and the shops that say this are already are doing $500,000 to 700,000 per year in annual business or even more. In my Management classes when further analysis of invoices takes place we find that shops are averaging 1.6 to 1.8 billed hours per invoice on basic consumer maintenance, 2.1 to 2.4 billed hours on diesel