I have seen them fail by developing a leak and I have also seen them blow out. Most of the time they will develop a slower leak.
In our fleet of transit buses, we don't change them as a scheduled maintenance item. We rely on inspecting them at regular intervals. Some checking of the rubber is normal. Serious cracking around the bottom where it folds around can indicate the start of a problem.
We really don't change that many. In a motor home application I don't think that it would be unusual for them to last the life of coach.