Why fuel Hoses needs Replacement

[sufi]

I have a quick question. I heard that the fuel hoses in the car needs replacement with time. I was kinda surprised to hear that because i thought it wasn't a big deal. So my question is, Why do the fuel hoses needs replacement?

[amitaj]

There are small pieces of rubber which are released because of flaking. They basically put an end to the fuel injectors which damages the hoses completely. That’s why they need a replacement. 

[ghassank]

I have never heard about this. So, when exactly should we replace these car parts? After certain period of time or after some mileage?