Hi
I prefer to use mine daily, as it helps me to keep track of what I am eating. The only time I saved them up for a weekend, I gained weight at weigh in, but might have something to do with my weigh in being in a Sunday, so a weekend of syn overload was probably not ideal!!
I think there are lots of people who save their syns up - do a search on here and lots of posts about it should come up.