There are those who have done 4 week wine kits to 5 gallons, and enjoyed them. That said, I prefer to try to add body to 4 week kits, so as not to lose those 5 bottles of wine. I have added bananas and or raisins to add body to these kits. A half dozen bananas or a pound of chopped raisins can add a lot to a 4 week kit. Another tip, is not to top with water, use a similar, inexpensive commercial wine, you will get it back at bottling.