While it is true, that not all bikes need rejetting... odds are against it...
Bikes are jetted to pass emissions under specific conditions, then shipped all over...
If you ride mostly in moderate temperatures, at moderate elevations, in moderate humidity, and don't modify anything, it might be jetted perfect...
... like,... inside a shopping mall ?...
...
People ride from below sea level to 16k ft, in temperatures from freezing to 100+, in deserts and swamps...
... and most, modify their bikes, at least a little...
Most people that don't rejet, are just afraid to...
If you go a step at a time, a stage at a time,... it ain't that scary. And you can always put it back like it was...
Just don't rejet, thinking you will make a fire breather... you won't.
More jetting doesn't equal more power,.. correct jetting does...
...