I would think the upsell happens in email before, during the shopping experience, or completely after the online checkout is done, not during the checkout proce

I would think the upsell happens in email before, during the shopping experience, or completely after the online checkout is done, not during the checkout process. Upsell during checkout is kind of a grocery store concept. At least those is common in my industry. As it's hinted to at the end of the article, better consumer habit tracking and targeted discounted low friction shopping cart adds with would probably make up for a lot of what is lost trying to port real world shopping behaviors into online stores (an utterly different experience)