Serpintine belt Question

It's been awhile since I have messed with one, what's the current thinking about replacing them ?, I was told before not to pay too much attention to surface cracks on the belt, or the mileage either for that matter, as long as the water pump and A/C & pwr.Strg are running freely, not to worry about the cracks.
Just checking to see what you guys think.
Rick

In my opinion, if you have surface cracks you would want to change belt as if could break and leave you stranded at the most inopertune time.
Cracks are a sign of wear and age.

In my 20 yrs of testing cars- I have NEVER seen a serpentine belt break- only fray- now I have seen them burn in two- from a seized component pulley-or be thrown off- but they do not break--Every serpentine belt I ever see on the road- usually at an intersection- that is in two pieces- has been burnt in two-- both ends melted-- but not broke in two...I have always made it an issue to see check belts for this failure mode- I have never seen one flat out break like the old vee-belts used to....even the frayed ones will let you know- but they don't break or make you walk....Just my humble observations..

Thanks for the thoughts, it's also my opinion, they don't break they burn on a stuck or struggling component, but just thought I would check on the latest opinions out there for my son who is coming in from Idaho today, He has abour 100,000 on his 99 Intrepid and the service people are making hm worry about the cracks, I have seen the racks on newer cars.
Rick