Originally Posted by spetz
And if they visually look fine, it's ok to leave them as is?
I agree. Unless the lines are abraded, a wheel gets hot, or the car pulls drastically, I wouldn't waste the money. In years long passed brake hoses, belts, and coolant hoses needed to be changed routinely along with master cylinders. Rubber product quality has drastically improved over the years. I can't remember when I last changed a master cyl.