I'm still pretty new to SW so I may be wrong but it's my understanding, at least on Extra Easy, that you should be using your syns daily so that's having 5-15 per day and that they are not carried over until the next day. If you had a day coming up where you think you will go over your syn allowance then you are able to flexisyn it, so long as it is planned - so if my birthday or a work night out was coming up I could say "ok, on that day I'll allow 60 extra syns, stick to that then just get on with life" and be back on plan the next day. However, this is really only for special occasions and not for a weekly occurence. I think on old plans people were able to carry syns over and some would save them up for the weekend and some people still do that and it seems to work ok for some and not for others.