The answer, just quietly, from makers charging ever-increasing amounts for their devices seemsto be two to three years before obsolescence kicks in and you're pushed to upgrade to a newer and maybe more expensive version.
That's good ongoing business for device makers and retailers. However, a recent Disputes Tribunal ruling disagrees with that timeframe, saying instead that we should expect at least five to six years' worth of full functionality from devices.
It's not a precedent-setting ruling, but the Tribunal may have opened up a can of worms by telling Noel Leeming to refund a customer the full $1,249 purchase price of an Apple Watch bought in 2015 that could not be upgraded to the latest version of the watchOS operating system.
At first glance it seems reasonable that devices costing well over a grand should last longer, and get software updates for the next five to six years. The first version of Apple Watch was sold as late as 2016.
When people bought a Watch, its full set of functionality included being able to receive software updates.
Unfortunately, that notion that devices should function fully and be supported for five years collides with the current reality. Even the latest, greatest and priciest technology available at the moment can and often will seem dated in less than a year.
Much of the blow-back on social media against the Tribunal says people are stupid if they don't realise this, and therefore the decision is wrong.
Looking at Apple's environmental documents and AppleCare extended support offerings, it seems two to three years is how long the company expects people to use their devices, although it's not consistent across all products.
That's not necessarily because a device is rubbish after three years. Instead, it's the result of intense competition between makers and developers who add new features in ever-decreasing cycles to entice buyers in a fierce battle for billion dollar markets.
New features usually mean that hardware that didn't exist just a couple of years ago is added to devices. It could be new sensor tech, faster networking, more efficient and faster processors and ever-higher resolution displays; or vastly improved cameras and foldable displays (that break) for smartphones.
Besides security updates and bug fixes, software upgrades are usually for powering new hardware features. Often, the hardware in updated devices changes radically which means new software won't work on old gear.
Each year, we get better, faster and smarter devices. Whether we need or even want them is another issue, and the environmental impact from a relentless and accelerating upgrade cycle is monstrous.
Even if the Noel Leemings of this world are forced to compensate customers unhappy with short product lives, it's clearly not a sustainable situation. The electronics industry has long been aware that it has to change, and ideas such as Google's Project Ara, a modular smartphone which could be upgraded in parts were launched to devise a solution.
Project Ara and others like it turned out to be environmentally unsound and technically infeasible dead ends, and we're stuck with costly (in every respect) devices that don't last as long as people would like. If that's not a massive innovation failure, I don't know what is.