This is a really good question. To be sure, there's a selection bias going on here, which I think explains why I have been able to reduce our household consumption by more than 50%, where in controlled studies (e.g. by utilities that have installed similar meters in their houses) observed reductions are around 15%.
But I would also say that I have done this over the course of several years, and while many reductions were ones I got with no pain or expense almost immediately, others were ones where I bought a new router, for example, that allowed me to get rid of my fileserver/router setup. I bought several BITS Smart Strips to reduce phantom load. None of these change my lifestyle in any way, but they do require some initiative.
But I would also say that I have done this over the course of several years, and while many reductions were ones I got with no pain or expense almost immediately, others were ones where I bought a new router, for example, that allowed me to get rid of my fileserver/router setup. I bought several BITS Smart Strips to reduce phantom load. None of these change my lifestyle in any way, but they do require some initiative.
Tom