I think typically the high speed (closest to the center of the carb) are the smallest, but that's not the issue here. If someone intentionally put that big air bleed in there, I would have no idea why. Dosen't mean there wasn't a reason, (I'm certainly not an expert) just that I can't imagine one.
Now you have me second guessing whether or not the one I am referring to is the idle bleed or the high speed bleed. Hrrrrmmm.... I wish I had brought the boat home with me now so I could check instead of leaving at the river When I looked at it I know I thought it was the idle circuit bleed but maybe I was confused as to which side the idle was on. I know that it was either the outer or inner bleeds but I'm now not sure if it was the closest to the center or furthest from the center now that you mention it. I do know that 3 out of the 4 were the smallest orificed bleeds by a large margin. They are so small that you could not fit a needle through them. Would that typically be the high speed? I have enough knowledge to generally do the basic tuning on my carbs and know enough to not mess with the bleeds beyond just spraying them clean with carb cleaner to make sure the passage is clear.