In reply to Joseph de Villanueva:
I have a full set of Rockcentrics on Dyneema (3-9), an extra size 3 I found somewhere and a couple of HB Quadcentrics (which are utterly ace incidentally). Last summer climbing on Cornish Granite I could have used even more than that.
I realise that is probably a bit excessive, but I reason that carrying the extra weight up every route is good additional training, plus my climbing partners are never in any doubt where I am at any point. I could never be a climbing ninja...