I think the cam loves wear as the lifters wear, so if your replacing 1 you replace the other. Just the same as motorcycle chains, if fitting new chain you fit new sprockets, so that the new parts can wear together, otherwise the old part would wear out the new part quicker.
I did a fair bit of research and got paranoid to drive the car, tbh now i dont worry, should it happen then ill repair it, if i wip the rocker cover off and see wear ill still have to get new parts. Iv got breakdown cover so if the s#*$ hits the fan ill get towed home and order the parts. Either way ill have to spend a lot on the parts......im personaly going to wait for that day, it may never happen in my ownership. Only on 60K.
Now iv said all that im gonna go hone, drive my car and probably break down due to the cams!