If you are a 70+mph distance cruiser, it probably doesn't make a huge difference,... but our bike is generally a putter, not a road eater.
A lot of my riding is relaxed 30 to 50mph on slow windy roads or in town and I'm barely on the throttle.
... but also consider, when you are starting to draw the majority of fuel from the slide,.. the pilot is still open and using fuel... It's running at all speeds above idle.
Plus,... my pilot/mpg info came from a Mikuni manual I read once, a long time ago, not my tiny brain... so I'll just go with it to make myself sound clever...