When you feel things are not functioning the way it is. On laptops, I previously jumped from 3rd Gen (i5-3210M) to 8th Gen (8550U), and now currently on 12th Gen (12700H+RTX 3060). Buying the U series was a mistake, if not I would have not gotten my 12th Gen laptop and probably bought a new one with the 14th Gen. My guess is, every 5-6 years should be good enough. Anything less than 3 years is not recommended unless you really need to extract and use every bit of processing power that the new gen delivers.
For the gaming scenario, most games above 1080p are GPU throttled and not CPU, so you might not gain a lot. My 12700H literally has the same performance as your 10700K and I would wager a guess, that it can last for 2-3 more years at least. Use the money to get a new GPU (if you game), or a better monitor.
When you feel things are not functioning the way it is. On laptops, I previously jumped from 3rd Gen (i5-3210M) to 8th Gen (8550U), and now currently on 12th Gen (12700H+RTX 3060). Buying the U series was a mistake, if not I would have not gotten my 12th Gen laptop and probably bought a new one with the 14th Gen. My guess is, every 5-6 years should be good enough. Anything less than 3 years is not recommended unless you really need to extract and use every bit of processing power that the new gen delivers.
For the gaming scenario, most games above 1080p are GPU throttled and not CPU, so you might not gain a lot. My 12700H literally has the same performance as your 10700K and I would wager a guess, that it can last for 2-3 more years at least. Use the money to get a new GPU (if you game), or a better monitor.