In the "old days" (back when I was a salesman) we utilized "system selling".  As a part of that system, we learned how to develop a commitment to buy (right now), get the offer in writing and get a "good faith" deposit.  The ONLY TIME we left the customer was when we took their offer and deposit to the sales desk.  Before we left them, we handed them our dealership "Why Buy Here" book with instructions to read the first several pages.  This gave them something (positive) to do while we were gone.  We were immediately sent back to our customer.  When we felt the stage was set (to present our first offer we picked up the phone and called the sales desk for figures and instructions.  We conducted our "drop, drop, split" like that...never leaving the customer alone.  The floor manager (closer) was always "hawking" the showroom floor and if we couldn't close it, in he came.

I know...I know..."old school".  But...it sold me a lot of cars and made me a lot of $$$.

The less you leave your customer alone, the better off you are.