Opinion is divided on what constitutes a satisfactory time-frame concerning the life-cycle of software products. Those more technically inclined see the importance of keeping current, whether it be in the form of a patch, or a major upgrade when their software is soon to be out of support. Others view updates as a hindrance, and are content using eight year old software as long as it runs okay, and does what they need it for. External factors usually dictate when they feel forced to upgrade. Windows XP’s later years were a testament to this. My father for example only upgraded from XP for two reasons; utilise more than 4 GB of RAM, and play newer DirectX 10 and 11 games.
Microsoft and Apple have held different attitudes over the years supporting hardware and software that isn’t so cutting edge any more.