Board preparation, at the end of the day, is more on the student than on the school curriculum itself. It's up to the student to supplement their free time with supplemental study materials like first aid, boards and beyond, sketchy, pathoma, questions banks (Uworld), anki, etc... There are things schools can do to hinder you in your effort which should be more important when making your decision, but I don't think that's the case with ARCOM. You will get plenty of dedicated time to study for your boards, as I mentioned above. Sure, there are mandatory lectures if you fall below 80% during the first 2 years, which may take away from your study time, but in my own experience, no one really cared if you showed up for mandatory classes as long you're not failing. I don't think board preparation should ever be the reason you decide to attend one school over another because there is no school curriculum that will solely be geared towards boards as you may have heard from many students at many DO schools.