Depending on the needle size, there really is limited scarring. Most of the props and trens that need frequent injections will go through a 25g needle and this is minimally damaging. As for the question of the cc's if you inject 3ccs in a site on one day or 1/2 cc in that same site for 6 days, the result isn't that different and in fact the 6 days would allow for easier absorbtion. The only question would be the injections themselves causing damage, but as theorized above, I don't think its that big a problems. So long as your total cc's to a site aren't outrageous you should be fine. The real key is to be observant of the inject sites and their repsonses to different volumes and compounds.