Banks are dependent on many variables, if the object ball is rolling when it contacts the rail or sliding, speed and throw. If you are straight on the mirror line and the ob is more that a foot from the rail then yes, center ball is consistant if the speed is the same, less tha a foot from the rail and the ob ball is sliding to the rail it will change the angle out, increase speed shortens the bank and decreased speed lengthens it.
Mark