Why? When does it work well or not?: It ignores the return on investment in SP & the risk. If you run <100% uptime or small resources with licensed operating systems and/or software, there can be low returns & also high risks. It can force a purchase which would be a bad business decision
Why? When does it work well or not?: Minimizes waste from unused RI’s, it ensures you only act when it makes business sense & effort can be recovered by making a change.
Why? When does it work well or not?: High amounts of effort required to know whether you’re actually losing money, and how much money. It can work in environments that have only a few different resource types running. This target can lead to large effort resulting in minimal gains or even a loss.