I weigh myself everyday too, and everyday the fluctuations are recorded on mpf, some days you retain fluids some days you don't. I don't expect to lose everyday - I can see the pattern developing with I look at my weight loss graph. Thing with weighing only once a week you still have those fluid fluctuations that skew you result.
I weigh myself every day and it really works for me.
I don't treat myself when I see a good number and I can make changes as soon as the scale moves up. I know that if I eat anything salty I am going to see a 1 pound gain the next take so I take that into account.
I keep on top of my weight by weighing daily, but it doesn't work for everyone, obviously.
It's best isn't it ? I "used" to weight myself every morning (and sometimes evening) after the first morning wee. If I liked what I saw I was : Oh great, that means that maybe I deserve a little treat today..always a big treat obviously or the opposite if I didn't like what I saw I was oh fuck it, lets not bothered anymore and I would go and eat a full box of fererro rochers.
So now I will only weight myself once at the weekly slimming club organised by my gym.