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Rubber deteriorates in about 4 to 5 years (or sooner). That is why tires are guaranteed for about 3 yrs. That is also why DOT requires dating on tires. I used to do mine every 3 years, but I now change hoses at 4 to 5.
In my experience, if the hoses still feel firm when hot, dont show any type of againg, like fade,cracking spongy, I would stick with what you got.
And, the bottom hose will last twice as long as the top because it is always filled will coolant. I've had dozens of cars with 100K+ miles and the original lower hose, never had one burst. Luck or ??.