Tech usually follows a 6 month cycle. Either something new comes out in 6 months or its a refreshed. Regardless there's always something new after 6 months.
Graphics cards and CPU's had been like this for a long time. This is also essentially Intel's 'tick tock' strategy, new release (tick) followed by a refresh approx. 6 months later (tock). Then another 6 months we get a new 'tick'.
Smartphones and smartphone SoC's are also ongoing like this. But I think they may be on a longer 1 year cycle.
It eventually reaches a point where the laws of diminishing returns start to take effect. I think we're starting to reach that point in smartphones now. CPU's and GPUs have long been at that point until the new game consoles come out (since they're on far longer life cycles like 5+ years, they get saddled with outdated hardware pretty quickly compared to the PC market).
Lower end devices and combined CPU/GPU hardware have much more headroom in that regard cuz they perform much slower than the high end counterparts (which is pretty much at its dimishing return point already)
In the end what this all means is you just have to take the jump at some point or you're just going to be waiting forever. the closer to your predicted dimishing return point the better as you'll maximize its longevity.