THC degrades over time doesn't matter where it came from. There are ways to slow down that process. In the end, what you started with will be lower the older it gets.
Its easy to perceive it as better when it tastes better(less harsh/smooth)
I find fresh plants/harvest the high is shorter, but can be more rushy to start and less complex then cured for 3 to 6 months (sallies only don't really do much of the fat ladies) I find the good effects early on in smoke 2-4 weeks cured usually increase their strength, complexity, flavours and duration after being cured but mediocre plants never seem to get better than mediocre.
That said I have friends who love kush and they swear it's only good for the first 1-3 months in the jar then a lot of the varieties degrade rapidly.
Isn’t it said that the long cure is better craze was started by a guy who wanted to sell last year’s stash?