I must be pretty gentle on bike components - when I hear about how often some people have to change out gear, and the states it gets in, it amazes me.
Until recently, I was running the original cables, inners and outers, and had only replaced the cassette once, the chain a few times, and the middle/large chainrings once on my 1992 Marin Eldridge Grade which I have ridden from new and done a
lot of miles on it. I used to be a courier for nearly 2 years on that bike not long after I got it as well, doing upwards of 70-100 miles a day.