Came across this old article and thought I should add in an important point in the discusion of rope life when lead climbing… We all know the rope won’t break but the most important factor in traditional climbing and winter climbing (where runners are often dubious) is the impact force on the gear when you fall.
Nice new rope = minimum impact loading so the gear holds. Old rope = much higher impact on the gear meaning the gear may get pulled out and result in you falling further or worst case scenario you hit the deck!
Also note that using two half ropes reduces the loading further. I always lead climb on two 8mm half ropes and once fell a long way onto a friend in a very dodgy icy crack and it amazingly held. I’m sure the reason was the fact it was a half rope plus the ropes were new!
On a final note if you use your rope for abseiling a lot or descending off long routes then this reduces the life of the rope rapidly. Same goes for indoor climbing.