If customers linger for a while on your help page, or in the checkout process, or any other area of your site, it may indicate a customer has some anxiety (or got up to get a coffee and a donut).
This is a good idea from an Internet Retailer article on how to employ live chat profitably:
Orvis invites customers to chat only when they are on certain pages, such as customer service. "We have a lot of stuff on the customer service page," Wolansky says. "If 15 seconds go by and you're still on that page, you're probably looking for something and haven't found it."
Orvis also offers chat to customers lingering on the checkout page. But Orvis does not offer chat on product pages, where visitors may linger reading reviews, examining photos, watching videos and comparing products. "Sitting there for a long time is not an indication you have a problem," Wolansky says. "I don't want to bother you."
With the help of web analytics, retailers can map out the typical paths taken by customers who buy, and identify deviations that indicate a visitor is likely to leave, says Kevin Kohn, executive vice president of marketing at chat provider LivePerson Inc. If a lot of visitors abandon after two minutes on a particular page, he says "when someone's there for a minute, 45 seconds, it's not a bad idea to reach out offering assistance."
Source: GetElastic