Daily weigh-ins (once daily) can be a VERY useful tool if they don't cause angst. I see so much scale angst (expecting daily weight drops, weighing more than once/daily and getting upset when it fluctuates are 2 examples) that I really think everyone needs to "weigh" this option for themselves (pun intended!)
Those who can view it with a grain of salt or (in maintenance) as a way to make adjustments to deter weight gain should use this useful tool. Those who get upset or frustrated should use it weekly, which actually gives us a good overall picture of what is happening but doesn't let any maintenance gains get too out of hand.
Those who freak out over +/- 1 lb over a day should probably stick with less frequent weigh-ins. Those who have made peace with the scale can view the daily fluctuations as useful info.
To each his/her own but when I see people freaking out, I will ALWAYS recommend staying off the scale between scheduled weekly weigh ins.
Losing weight is hard. Maintenance is hard. Being fat is hard. Pick your hard. (-Ishbel)