A point I would consider of note is that it has long been known that a small degree of choke (e.g. the UK improved cylinder) gives a much more consistent pattern than true cylinder (as well as a slightly denser pattern) and is also thought to be more consistent across different cartridges.
I am a rather average shot (as said above, many game shots such as myself are not very good by overall standards!) and I find that improved cylinder or quarter choke in the right barrel and quarter or half in the left barrel (which is a pretty common combination in a UK sporting gun) suits me just fine.
Very good point. Even the smallest amount of choke will generally improve the pattern, even if it doesn't necessarily make it tighter. Even a few .001" of choke will give resistance to the wad as it exits the bore and help it separate from the shot column, and reduce any negative effects the wad might have on the pattern.
