A 2-chain+ solvent system enables you to fit a new, clean chain and deal with the the dirty one some other time. This is especially useful for winter commuters when you really need to clean your chain but the conditions are too uncomfortable to be doing much maintenance.
Keep one chain solvent-cleaned and lubed in a jar. Whip off the old chain by its powerlink and dunk in a jar of solvent, Take your clean chain and add to bike.
At some point in the future you can clean and lube your dirty chain.