In general the holes work out better for indexing and the degree markings work out better for angles. They can however cross over and if you are careful to line up your marks, you can get fairly accurate indexing with that unit. The gear ratio between the worm and worm gear reduces the error in the hole plate or mark by that ratio. For example, the 3″ unit I listed has a 36:1 ratio and any inaccuracy in lining up your marks will be reduced by that amount. The least accurate method is to use a direct hole plate as any inaccuracy in the holes will directly transfer to the part.