What is the lifespan of a gearbox?

I'm curious to know, what is the typical lifespan of a gearbox? Do they vary depending on the make and model, or are there any common factors that can affect their longevity? Is regular maintenance essential to extending their lifespan, and if so, what kind of maintenance should be done? Are there any warning signs that indicate a gearbox is nearing the end of its life? Additionally, is there a way to predict the lifespan of a gearbox before it fails, or is it more of a case-by-case basis?