This is a difficult answer but I will try and answer it in a simple way.
When you do a facelift or any other procedure you are trying to make the patient look fresher and possibly a bit younger. Everyones ageing process is progressing at a very different rate. We have seen this even with twins.
Its all about making the patient look fresher and younger off his or her age that means making a 60 year old look a younger looking 60 year old rather than taking ten years off and making the patient look 5o.