I am usually aware of the edges of my photo and keeping them clear of extraneous contact. When I crop a cityscape, I am aware of the buildings and I try to keep even the small ones on the edge whole or split in a way that works for me. When I shot a butterfly in a garden recently, I paused before pressing the shutter knowing that the surrounding flowers were going to be severed in a haphazard way. I shot anyway and am quite happy with the way it turned out.