It depends on the speed of your airplane, and the distances you are flying. In slow, really slow airplanes, a 1/4 mil makes sense.
On the other hand I used to find a 1 mil chart more useable for long flights, say 600nm.
Now I stick to 1/2 mil. There certainly is a chance of error in swapping scales, as there is in using a ruler with mulltiscales.