GW, I use a similar method. My logic is that I use WD40 as a degreaser (ie disolves all the paste in the chain.) I then let it dry and then apply proper lube just before next ride.
Obviously finishline degreaser would remove this paste better, but I am always worried about leaving a bit of degreaser inside the chain. You only need a tiny bit to completely mess up the surface tension properties of the lube.