In reply to Rick Graham:
Probably about 5 minutes above the top of the buttress, if I'm at that point though I'll usually just take the hit and descend down into No5 but realistically there's probably not much time difference. If descending from the summit then I'd go down Ledge Route, across the gully and into the Ciste. I actually quite like going down Tower Ridge at the end of the day, rounds things out quite well with a bit of an alpine feel after a long rock route.
I've only done King Kong on that side of the cliff where you could get to the Titan's Wall abseils but I'd always much prefer to finish the route properly to the top of the wall, even if the route is much easier by that point. Those top pitches end up being neglected and getting dirty as a result of folks taking the quick way down and "ticking" only the harder sections.
Ed; I think descending No4 in summer is now advised against due to the discovery of some rare upland plants near the top during the NF survey a few years back which should be left alone. As you say though, not many folk will feel the need to do it twice!
Post edited at 23:09