I am new to sw too so haven't tried this, but it sounds like a really good concept. Basically if you know you are going to go over your syns on the odd occassion, you sit and work out a realistic amount you could stick to. You then make sure you stay inside this. Next day, you carry on as normal with your syns - you don't cut back. Obviously it will affect your weightloss for that week, but it means you stay in control, and shouldn't feel guilty, and you don't punich yourself by cutting away back for the rest of the week. Altho it will affect your result, pschologically I think its really good.
Obviously you wouldn't want to be using this technique a lot though.