1) Do you believe it's worth the effort to clean your bore between shots, and if so, how do you do it?

2) How much do you typically see pattern centers vary, from shot to shot?

3) When you change choke tubes, then come back to a prior choke tube, does this effect your pattern center relative to the last time you used that particular choke tube? (My thinking on this last question is that if you screwed the tube in just a little more or less, you could shift your pattern center.)