Flexible o-rings last a long time if you treat them right. If you don't, they can fail early and cause great trouble. Whether you are using tiny o-rings for a sink faucet or larger o-rings for industrial projects, you have to be aware of the conditions that will make the o-rings more likely to crack or break. Some of these are difficult to avoid and warrant keeping a very close eye on the o-rings in those situations. When you know the o-ring has experienced tough conditions, that gives you advance warning that the o-ring might need to be replaced.
Too Much Pressure
O-rings can withstand varying levels of pressure, depending on the o-ring's construction. Go outside the range of pressure that the o-ring can tolerate, and the o-ring will be crushed. That can cause splitting and breaking, leading to leaks and other problems. Always use o-rings that are made for the specific purpose you need them for; don't assume size or material automatically makes them perfect for everything. And do keep checking them occasionally to ensure nothing has gone out of bounds and started crushing them.
Exposure to Extreme Conditions
O-rings are made of materials like EPDM, silicone, and similar materials. And, like anything made from those materials, these o-rings can expand and contract when faced with extreme temperatures. The repeated expansion and contraction eventually degrade the material. They can also dry out, further promoting cracking. All you can really do here is try to provide as much climate control as possible along with using o-rings constructed to better handle extreme heat or cold.
There's always the chance that the problem with the o-rings is accidental, such as scraping against it and accidentally creating a tiny tear that you can't see, but that can affect how the o-ring performs. Being very careful around the o-rings and inspecting any that you've hit can help prevent problems.
Finally, o-rings can be too old. They can dry out naturally and degrade just like any other material. If you've had o-rings in equipment for a long time, inspect them to ensure they do not appear to be drying out and becoming ready to fail.
Constantly inspecting o-rings and similar parts helps a lot, but you need to ensure that the o-rings are being used properly in the first place. Get o-rings for your facility from manufacturers who make them to meet the specific conditions in which you need them to work.