Admittedly there is some merit in what you say especially with that 30mm ballistic drop. It would make sense to push that convergence out a little further to counter the "drop" in a high speed firing turn. I have my Yak cannon 25 yards further out than the wings guns.
I use the F6f alot with 6x50's convergence set to 275. My kill zone is typically 200 to 300 yards. The 50's fly fairly flat and straight. The disadvantage, for want of a better expression, is you need to hold hits on target a little longer than cannon planes. Hence the need to get closer in for effective damage in the shortest period possible.
New guys in general have an instinct to fire at wildly ridiculous distances. Some will push the convergence out to the max to compensate and some will actually be successful with the spray and prey, at distances none of us would even attempt. By encouraging the new guys to shoot closer with a convergence suited to the ballistics the new guys will realise, at least I hope, that they have to work for the kill. Having said that it is only right to say "each to their own", Meaning some folk are well suited to getting, in my opinion, long distance kills and have their convergence set to reflect their preferred ability.
Yea I can see what you are saying, but I've always set my convergence out to around 300 to 350 in pretty much every plane. As I said I don't fly 50 cal planes like the P47 or P51 very often. I'd think those planes are more of a BnZ plane so to me It's a want to be able to fire as far out as I could not wanting saddle up and slow down for the kill. Seems like keeping your speed is extremely important in those planes.
I do however fly the P40E and the Spit1/Huri 1 from time to time and my convergence is set at 350 in al those. In those planes, most of the kills come in the 200ish range I still think it's important to be able to shoot a little farther because most other planes will easily out run you. On the flip side even with convergence set out @ 350 I still don't have much issues killing planes at closer ranges.
Just seems to me the having the convergence set out further gives you more opportunity to get the kill and doesn't limit you as much. It also doesn't mean you spray and pray because I do very little of that. I'm big on not shooting unless I think I can hit the target.