What would be the reasoning for mixing different sizes jets in a carburetor?

For example I have a Holley 2245 which the service paper says:

install the lean jet on the choke side and of the bowl and the richer on the pump side.

I tried doing some lite googling on this and didn't really find an answer, but I did run a cross a motorcycle thread titled"Different jet sizes between cylinders".

Reasons given where for cooling and the length difference of the exhaust pipes.

I myself have no idea. My best guess would be it has something to do with the accelerator pump or one side of the engine "works" better than the other but, you wouldn't know that unless you put 02 sensors on both exhaust pipes, right?

And if one was to re jet such a carburetor should the above rule still be honored?

Is this something thats still done on modern after market carburetors like the ones you can buy at the local parts store?

 

Simple answer. Because of the length of the intake runners & design..

 

Alright if thats the case, then I should make sure during tuning that the pump side (left side) has a richer jet. I wonder if that side is richer because the exhaust pipe on that side has to bend to join with the right side. The right (choke) side is a straight shot right out the back of the truck, no bending.

But, I still think to know for sure how each side is running I would need an 02 sensor on both sides as opposed to a single sensor after the y pipes or at least moving the the sensor to each side and tune separately.

Am I making any sense?