Twice a week.
Once on weigh-in day (their scale), which is Tuesday, and once on Friday morning to 1.) see how the week is going, and 2.) to plan for the weekend.
I'm up one lb. this morning but I've got a 10 mile run tomorrow morning, a 7 mile run Saturday afternoon, and another 10 mile run on Sunday morning on tap. So I think that pound+ will be gone by next Tuesday. Oh, I'm training for a relay--don't usually do this much back-to-back running!
And if the weight's not gone? I agree with everyone who has remarked above that it's more about how we feel (or more precisely how our clothes feel!) that is the biggest determining factor (mood, needed changes, etc.). And right now I am a "perfect/comfortable size 6 petite" and I'm loving it!
P.S. I'll probably weigh more often when I'm on maintenance to do as Murleya 1 does, "watch for trends" and determine my carb level tolerance.
HAPPY FRIDAY EVERYONE!

. So I gave my scale to my bf last night (it's not in my house, in fact he left it in his car trunk so I wouldn't be tempted at his house either) so that I wouldn't be tempted to jump on. I was bad enough to get on it 5-7 times on a Saturday or Sunday. It's been very hard for me today (my first day without weighing myself)...but at the same time I'm not using the number to beat myself up. 
Ha-ha! You are right, follow the protocol, have faith and I will lose weight. I just need to keep reminding myself of that. Maybe I should make that my mirror mantra...
. I know I need to chill out!
I step on the scale each day and find if I do I operate in a different realm if I am down ...more kick in my step more attitude I feel like I pull my stomach in as I am walking . It's so funny but I really do. I guess it rules ....I have gone down almost apound a day since being on this program...Since May 31st to this day a weight loss of 21 lbs ..During the monster time ...(TOM) up 2 but then down. Sometimes I get afraid to get on..It's crazy to be ruled by this....But my inches are huge and I feel full of energy..I really think this is going to work.....Please let it work..Thank god for all of you to talk to really I mean it....I come her often for support and get it.....Bless you all..