Our consultant used to advise against weighing at home (assuming you attend a class), for two opposite but still negative reasons:
1. If the scales show you weighing less than the class weigh-in, you might feel you're doing great, and can relax a little during the week, eating more syns than you should, which will affect your class weight loss.
2. If the scales show you weighing more than the class weigh-in, you might feel depressed and frustrated that you're not losing no matter how hard you're trying and just give up.
While I can see the reasoning behind this, I think the main points are that you should stick to one set of scales for consistent and reliable information, and that weight can fluctuate up and down day to day, so weekly weighing only will be more indicative of actual progress.
Saying all of that, I weigh myself about three times a day, sometimes trimmming my nails or removing belly button fluff between weigh-ins to grab an extra ounce or two