Below is an excerpt from HBR quantifying the short life of online leads.
Companies that contact potential customers within an hour of receiving a query are nearly seven times as likely to qualify the lead as those that contact the customer even an hour later—and more than 60 times as likely as companies that wait 24 hours or more. These results come from analysis of 1.25 million sales leads received by 29 B2C and 13 B2B companies in the U.S.
I can't help but think of the ABC scene in Glengarry Glen Ross in terms of leads:
HBR article by James B. Oldroyd, Kristina McElheran, and David Elkington