During fermentation yeast does all sorts of things. Some of those things don't taste so good but given a chance the yeast will also clean up after itself. This is why it is beneficial to leave a brew for a time following fermentation.
Racking to a secondary fermenter for the purposes of a secondary fermentation (or secondary stage of fermentation) still leaves enough viable yeast to carry out this job. Leaving a brew for too long on yeast can supposedly lead to vegemitey flavours caused by autolysis BUT while it is a possibility, many suggest that it takes a really long time (eg several months) before it's a major worry. Don't rack simply to get the brew off the yeast. Yeast is good. Yeast makes beer.
I'm not 100% sure on the science of it but my brews improved tenfold when I started leaving them longer (admittedly at the same time I started fining, cold conditioning, racking and concentrating on temp so any and all might have made the difference). I'd happily recommend stable gravity + extra 3 -7 days. Cold conditioning during this time won't hurt a bit.
