I like shooting at a NFAA "Hunter Face" All black target with a white dot -- I shoot better and it helps me concentrate better.
I find it difficult to shoot a "Field Face". With the primary color being white it has less contrast than the Hunter Face...
Now this is my opinion, take it or leave it. When I find a target or situation that I find "comfortable" while shooting, vs. one that is not so comfortable; I make a concisous effort to work on the uncomfortable situation MORE!
Again my opinion, but once you have your form elements down, you know how to shoot, you've done before and you've probably done it very well at different points in time...So the question becomes why sometimes and not others?
You can probably pick apart the form elements that contribute to any problem, but my opinion is all problems (once you know how to shoot) stem from stress, lack of confidence or fatigue (mental and physical)--In short most shooting problems begin in your head.
So I'm of the opinion that the worse thing to do is to hide in your comfort zone. If you don't shoot dots well, make an effort to shoot dots once a week. If you don't shoot well in front of people, invite a group over to watch you shoot once a week or make an effort to shoot in a couple of tournements each year.
Step outside of comfort zone and face stressful situations head on. It will make you a better archer and Bowhunter -- After all, Bowhunting is facing stressful situation an executing at a specific momement