I think they are not purely cumulative because I assume that consumer have a it of slack in their decision/budget and that each optimization consumes some of th

I think they are not purely cumulative because I assume that consumer have a it of slack in their decision/budget and that each optimization consumes some of this slack. The basic idea behind 1 and 3 is to stress out the consumer into believing that he may miss a sale. I think that stressing them out with 1 or 3 more or less gives the same result and does not need to be applied twice. Real scarcity exists, but this paper gives an incentive to create artificial scarcity. I have seen a lot of websites mention low stocks but none mentioning backorders or restocking estimates. Saying "Only 3 items left" has a very different effect than "only 3 items left but 100 more arrive in 2 weeks".