Let's try a thought experiment. We have two ramps. Ramp A has a 45 degree incline. Ramp B has a very, very slight incline. We measure how long it takes a ball to move the same distance (say, along 20 feet worth of ramp). The ball will take much longer to move 20 feet down ramp B than it will to move 20 feet down ramp A.
Gravity is pulling straight down on the ball in both cases, and by straight down I don't mean down the ramp, I mean toward the Earth. Neither ramp moves the ball along the gravity vector, but ramp A is much closer to that vector than ramp B.
Any vector can be considered to be the vector sum of two component vectors. For example, a particular 45 degree vector could be the vector sum of a horizontal vector and a vertical vector.
The only part of the gravity force vector that causes forward motion down the ramp is the component of the vector pointing in the forward direction. If the board were perfectly flat that component would be zero and all of the gravity force vector would be a single component pointing straight down towards the Earth and contributing only to static deformation of the ball and the ramp.
So fundamentally, you have to account for the difference in the component of the gravity vector applied to motion. In the case of a ball dropped out a window of a tower, that component is wholly coincident with the gravity force vector itself. In every other case it is less.
Beyond that, you have to consider frictional forces which convert gravitational energy into conductive, convective and radiative heat energy that increases the temperature of the ball, ramp, and air (or radiated into space). That will depend on the angle of the ramp also, as well as the materials which the ball and ramp are made of, and the weight (not mass) of the ball, since that can cause dynamic deformation, or bring more of the ball surface into contact with the ramp, or bring the ball microscopically closer to the ramp, any of which may aggravate the molecular attraction which constitutes friction. Modern golf balls are dimpled and that irregular rough surface in contact with a rough wooden surface would tend to increase friction.