I had some greenware pieces and buckets of dried scraps that had been sitting in my studio for some time.
Working with paper clay, I do not throw away any bits, including trimmings, broken pieces, etc. The cost of paper clay being more expensive than regular clay makes all paper clay artists misers, I think. You can readily make paper clay slip for "gluing" your pieces together from your scraps, use them for surface texture treatments, or reconstitute the dried paper clay back to a workable condition.
I make small scale models of a concept, to see if it will translate well from a 2-D drawing to a 3-D form. This is a great way to anticipate any problems I may encounter before starting on the real thing. All this clay can be recycled so there is no wastage.
The picture shows the way I recycle my paper clay. After slaking for a day or two in a 5-gallon bucket, I mash the paper clay into a thick oatmeal consistency, pour it out on top of bed sheets and let the concrete in my patio soak up the excess water. This may take some time to get the goopy oat-meal like paper clay to a kneadable condition. I knead the paper clay into manageable blocks and I have fresh paper clay ready for use.