Cessna recommends replacing the flexible brake hoses every five years or 1000 hours. Of course, for those flying under FAA CFR Part 91, the manufacturer’s recommendations are not requirements as far as the FAA is concerned. One can choose to continue with these hoses in operation as long as the owner wants or until they do not meet the requirements for airworthiness.
Similarly, the person performing an annual inspection can only require replacement of a flexible hose if it doesn’t meet the requirements for airworthiness. Otherwise, the maintenance provider may only recommend replacement.
The requirements for airworthiness are that the hoses meet their type design and are safe for flight.
A check for safety of flight would be signs of leakage or embrittlement. Embrittlement would be if the interior of a hose was dry rotted and bits of the inner wall were breaking off. To check for this a mechanic would flex the hose and listen for a crunchy sound not unlike breaking potato chips. Checking for meeting type design is what usually triggers an airworthiness required replacement. The original protective outer casing is a type of plastic. Over the years this plastic gets very hard and dry, then just starts to fall off. The lack of this outer coating isn’t a concern for immediate failure of the hose, but it certainly doesn’t meet the original design of the hose.
Few owners are aware that their 210 brake system includes flexible hoses. There are only two, one attached to each brake master cylinder. That’s the cylinders mounted just forward of the brake pedals which also include the brake fluid reservoir. The hoses are routed from the master cylinders under the floor, around the electric fuel pump to a solid line near the left fuel header tank. Access is a pain which is partly why these hoses are frequently ignored or just not noticed.
During landing the failure of one of these hoses, and the subsequent loss of braking on one side, would likely end in a runway excursion. A highly recommended precaution is to check for brake pressure after landing gear extension before every landing. Landing without braking on one side isn’t a terrible thing to deal with as long as you know it’s coming.