Once a week is enough, but I am one of those people who weigh themselves daily. My weight fluctuates during the week,but I consider Sunday's weight to be my official one for the week. It is VERY easy to get discouraged. However, after almost 10 months of SB I can see the daily fluctuations are usually because of hormones, food choices, lack of water or even intense exercise. I don't beat myself up, but if my official weigh in is higher than the previous week, I make extra careful choices
Good luck and welcome