Sometimes I weigh daily, sometimes only like once a month. I know if I'm eating well and exercising, then it doesn't really matter what the scale says. If it's going to show a loss in pounds I'd rather it be a permanent one rather than a daily fluctuation. I don't keep close track of my daily weight like many have said (though I think it's a neat idea and might if I had better access to a scale) but should also say the first poster mentioned weighing at the gym I think? I hope that wasn't on a different scale, I don't really trust any single scale, just pick one and stick to what it's telling me for loss and I'll worry about my "real" weight when I'm at the end of my journey.
I think weighing daily is smart, but I'll bet that studies like the one posted have success mostly in that people are *thinking* about their weight on a daily basis; thinking about diet, exercise, and healthy habits. I think it's the thought that counts, not so much the reinforcement of the number. I haven't found good or bad results of the scale to always have the same effect on me, sometimes a loss inspires me to keep going and sometimes I trick myself into thinking I've "earned" a treat