When I'm on a good cycle, eating well and working out, I weight daily, and it helps me stay on task. When I fall off the wagon for either diet or exercise and I know I'm not doing well, I avoid the scale until I climb back on the healthy-eating/exercise wagon again.

I like to weigh every day. I don't fluctuate much day to day, just for about 2 weeks of the month building up to guess-what? I can just take that into account, and there is always a little drop afterward.