"Well, all I can really tell y
"Well, all I can really tell you is that the local Honda dealer that I get help from told me about 4 years ago, (when I bought the first one that I replaced) that he almost never sees a problem with the belts. Since then, I have found him to be right through my own experience.
The two belts that I have replaced in the last two years were because I found the timing belt drive gear on the crankshaft for those two engines had come loose because the nut that holds it down had backed off. The nut, the spacer/belt deflecter, the gear and the drive key were all damaged but the belts and crankshaft still looked fine. In both cases, I replaced the belts because I was replacing the gear and thought it was the right thing to do, not because I saw a problem with the belts.
I would say, though, that nothing lasts forever and those belts will deteriorate over time just from being on the planet Earth.
I work on rental engines that are going on 8 years old and we came up with a formula that says that they work, on average, 2 hours a day 350 days a year. We came up with this as a service interval guide for oil changes, tune ups etc. because we don't use hour meters or logs. So, doing that math, many of my engines have over 5,000 hours on them, at present, and I look at those belts all the time. So far so good.
But, at 2,000 hours, my old pappy would say this: "That belt's been workin' pretty hard for a pretty long time and it don't owe anybody a dime". That would be his way of saying get a new one but from what I've seen so far I'm not sure I would.
Another thing ol' pappy would say about what I've just written would probably go something like:
"oh yeah, why that's as clear as mud boy!""