Lifespan of radiator hoses and serpentine belts

All belt or chain in many cars is stated in your manual book or service manual for that car, every car have different manufacture safety standard.

For common vehicles this is around 60K miles - 100K miles. (~100K-200K Kilometers) although is stated with 100K miles if you looking at your serpentine or fan or timing belt is a bit worn, tacky, stripped; it's better you change it.

some fan belt in many mass build car is driving the alternator with built in vacuum for braking system, once the fan belt is broken you will pray to god because you will lose your brake.

same with your hose. once it start leaking or broken while you drive, you will not notice it. because it under engine hoods. there is no sensor telling you that is broken or leaking in old model or even newer model. the temperature indicator is pretty slow rise. And how many times did you look into temperature while you drive?

how to check : the radiator hose is pretty much rubber with 2 or 1 fiber lining, it's almost solid like your shoes sole. if you can bend or squish it without much effort this is indicating your hose is need to be replace. (you will know the difference) but this is not always how to indicate, because i have one car with sturdy hose but it's leaking like crazy because apparently the hose is brittle (but it's hard to squish it) Change it with same part number or original hose, if no one sell original one, buy the hose that have fibre lining inside, never buy the hose without any fibre lining (it's bad, it will degrade so quick)

Hose design has improved greatly in the last 20 years. Because of the use of better materials it is difficult to judge the condition of the hose based on appearance. Even with the old hoses you often had to remove one end and see what the inside looked like. I think any answer will be anecdotal based on individual experiences. My last two vehicles were 18 years and 16 years old and never changed a hose on either one. I did change and flush the coolant every 5 years though. If you happen to live in Texas or Arizona or somewhere that sees 120F on a regular basis you might see earlier failures. As @SolarMike has stated the interval should be based on your level of accepted risk. Based on my experience I would think 10 years would be reasonable. If I was going to be 150 miles from civilization I would want hoses less than 5 years old. This would be based on the level of risk I am willing to take.