Originally Posted by FBinNY

I run multiple chains for each bike, rotating them when it's time to re-oil (or 800-1,000 miles on the road and commuter bikes). The advantages are

1- that I can clean and oil off bike which is always more effective
2- I'm never under the gun about having to re-oil since there's always a ready chain on deck ready to install
3- the chains tend to run smoother because they're better matched to the wear condition of the sprockets
4- I'm not limited to the 1/16"/12" guideline since I'll never put a new chain onto the cassette. Typically I'll be able to run to almost 3/16"/12" before it becomes unworkable.

The biggest benefit of the whole deal is not being limited to the 1/16" guideline, so when I compare to the sequential method (asuming all else is equal) I get all those bonus miles after the last chain reaches the guideline.

Almost everyone I know who has adopted this approach reports longer cassette life, whether they rotate 2, 3 or 4 chains, plus the other benefits. However to be most effective, it calls for reusable connectors, so the connectors and chains can be kept in married sets.

FWIW- the only cassettes or freewheels I've ever replaced due to skipping are one on my old road bike which I retired after 50,000 miles, and one on my commuter which is now at something over 20k miles.