But if I spend a month refactoring and only get a weeks worth a benefit before the project is scrapped it wasn't worth it. If I get a month back before the project is scrapped it wasn't worth it (I could have been working on something else instead). Unless/until we know how to quantify how much gain will be got back, and how long it will take to get that gain back and so we cannot do a proper economic analysis if it is worth it - but that is what we need.
But if I spend a month refactoring and only get a weeks worth a benefit before the project is scrapped it wasn't worth it. If I get a month back before the project is scrapped it wasn't worth it (I could have been working on something else instead). Unless/until we know how to quantify how much gain will be got back, and how long it will take to get that gain back and so we cannot do a proper economic analysis if it is worth it - but that is what we need.