Im not sure where you are doing your research.
But on these engines with siamesed intake ports you are "full of misinformation " to say it nicely.
A single carb is the least efficient method of fuel distribution with a design such as this. Cyls 3 and 4 run rich and cyls 1 and 6 much leaner. Now aint that fuel distribution efficiency? Oh its adequate, but its not more efficient at all.
the most efficient is a carb for each intake port all 3 balanced to provide the best fuel distribution and atomization for each set of cylinders per port.
Multi carbs good only at high speeds and WOT?
I think you missed the boat on this.
They are great in all ranges on this engine. Better fuel distribution to all 3 ports and much more efficient fuel atomization.
No problem you can believe what you want, but the reality is quite the opposite of what you are claiming.
I can go on much further to refute your claims and to demonstrate how a multi carb set up works more efficiently in all ranges, the benefits and the increased HP and fuel economy.
However you would come up with some reason contrary, its quite evident you dont like multi carb setups and better exhaust flow for your own uninformed reasons.
I believe others have also stated their responses in disagreement to your beliefs.