The importance of knowing who your customers are translates directly into your ability to stock what they need at the front end. Customers spend (on average) almost 35 minutes in the store and over 5 minutes at the checkout. This is valuable time where you have a customers uninterrupted attention.
Conversion rates differ by lane type. While the highest conversion rates occur at regular lanes where shoppers wait longer, conversion is lowest at Self-Scan lanes where the shopper is distracted by performing their own transactions.
Source: Front-End-Focus