I'm really new to this so not really sure. When you enable billing your free limits increase (weird I know) and I don't think I've actually incurred any costs a

I'm really new to this so not really sure. When you enable billing your free limits increase (weird I know) and I don't think I've actually incurred any costs as a result. I don't really know how well optimised my site is so it may be that it could scale up to those numbers if the back end was better? That said, all the limits are daily on app engine so maybe it was just that the spike was big enough to bust my daily limits?