Nitro, I've only had to tune once last year
My car is still running fantasic, and it's still as fast as it was when I first got it.
It may vary between cars, but from my understanding if you drive it right, treat it right; You can get away with slight adjustments here and there, but the more you touch the carb, the sooner you'll need to replace it. Constantly screwing the HSN and LSN will begin to do almost nothing, that's why on a lot of noobies cars, you'll notice the needle sits almost all the way to the bottom, that's what I'm getting at, play with it for a few weeks, until you find the optimal tune for the car, then leave it, because everytime the car cools down it will run how it originally did.
You want to find a tune that works well with idle, low, mid, and high rpms of course.