Assuming that the project went on for 6 months before Touma stopped it, Accelerator would have had to kill roughly 55 clones each day to kill 10,000 in time. That seems fairly ridiculous. Assuming he sleeps for 8 hours each day, he would then need to kill about three and a half clones every hour, and that is if he does not eat, use the bathroom, go to school, or do anything besides kill clones. Given that each one still took him a few minutes to kill (because he toyed with them) and that he needed to transit between the scheduled combat locations, the rate of killing just seems infeasible. Additionally, I severely doubt he could psychologically deal with so much killing. Even a sadistic maniac would probably get bored after killing a few hundred people, and Accelerator seems more uncaring than outright sadistic. Did Kamachi just not do his math when figuring out how many clones there were?