I buy 3 chains for a cassette and alternate their use, never allowing the roller spacing to increase by more that 8-9% before changing to the next new chain in the rotation. The spacing between roller varies between brand, but usually starts at .200-.210 inch. Campy chains have the smallest initial spacing. The partially used chains are kept for future use. After all three chains have had their first use, the rotation starts again, but at more frequent intervals, like any time I have a chain off for cleaning. With this process you will never encounter new-chain skip on worn cogs. Rotating chains also allows them to be used far longer because you don't remove them prematurely to "protect" the cassette from having enough wear to cause new-chain skip.
Seems like a very good idea and I happen to have 3 chains for my bike in the house (on on bike measuring 0.6 on my park chain wear measure tool) so it would be a good time to swap it out if I want to give this a go.
What do you guys think.