Classic example is recommendations on a product page. If the personal recommendation service is not available / slow to respond, you might fall back on recommen

Classic example is recommendations on a product page. If the personal recommendation service is not available / slow to respond, you might fall back on recommendations based on the best sellers or even fall back further by not giving recommendations at all. Recommendations are not necessary, and not showing them will significantly affect the bottom line, so you don't want to skip them if possible. But not showing the product page (in a timely manner), because the recommendation engine has a hiccup, is even worse for your bottom line.