Firstly, I'll use the lights in whatever room I'm in when I need them and will turn them off when I don't need them.
Secondly, the amount of electricity saved is tiny. If you are sensible anyway you'll only have the lights on in whichever room you are in. Let's say there is 4 of you at home, you may have 4 rooms lit. I'd be surprised if that equates to more than 400W of usage. 400W saved is tiny.
This is just a fad and is ignoring the real issue. Will it save electricity? Yes. Will it make any kind of difference? No.
It's also ignoring where you get your electricity from, if you get your electricity from a dam (say Vegas) then your electricity is created without the use of carbon emissions through burning a fuel.
Btw, I estimate that our total house has about 1KW maximum in light bulbs. That's about a third of your average oven. For a 13 room house btw. 200W of that is in the kitchen.
Want to impact with what people use for lighting? Make the only bulbs purchasable the fluorescent or low-energy bulbs. Your normal 60W bulb uses nearly all that power as heat. Probably about 1W of that is used as light. We've got a 15W low-energy bulb in this room and it's as bright as an 80W normal bulb.