I consider the sweet-spot to be between 1000 - 998, which gives about 120 shots or 90 shots between between 1015 and 1010, which if I were that good a shot, would be nirvana
At 25 yards, with lubed CPL's and Daystate FTs, sometimes I can put 10 in the same ragged hole, but other times I shoot all around the 10-ring, but I can't explain why. I use the "A-Team" 20-spot sight-in target for practice, and it's helped me.
I also wish I knew why I still get fliers.