I think there is no right answer, it depends on how you handle good (or bad) news.
Personally I like to weigh multiple times each day (use scale at gym and home). I find it kind of fun to see how my weight fluctuates both throughout the day, pre/post workout, and from day to day.
However I fully understand that my weight is not a linear downtrend. Instead it is like a stock that is slowly going down in value. There are a lot of little peaks and valleys inside of the overall trend.
It's fun to see a new "all-time" low on the scale, but I understand that it is likely that I will see several days of higher numbers before I see another low, due to food in my system, water, etc.
I've seen my weight drop 3 lbs overnight, then I will have a "perfect" day of eating and exercise and see it go up by 2 lbs the next day. By weighing often I can get a sense of just how much influence water, food being digested etc plays a role.
If I think of "normal" being say middle of the day with moderate food/waste in system, moderate water weight, and other factors I expect to see up to 5 pounds + or - based on environmental factors. That's a total of 10 lbs of leeway.
So when I see a new all time low, I know it is likely that partially it is non fat loss factors that is helping a bit. However if I average all weights throughout a week, I would expect my weight from week to week to be lower the vast majority of the time.
That's kind of the reason that I don't like weighing once a week. You might catch an "all time low" one week and next week be say +1 pound even though you've actually lost 1-2 lbs just because you are catching yourself with slightly different environmental factors.
So short answer is I weigh often, but only focus on overall trends not on little spikes or dips.



Seeing a loss keeps me excited and focused.