I have gone through a multitude of trials to figure out the perfect shot for Hole 4 on the Grassy Land level. If you're able to pull this off in a run you can finish Hole 4 is less than 5 seconds. When I timed it I got was 4.75 seconds.

Here's the clip of me doing it:

The slow motion is to make it easier to see the exact point in which I take the shot to get the ball to fall perfectly in the hole.

https://imgur.com/gallery/X88O7oW

This is an image of the exact amount that you need to hit the ball (NOTE: DO NOT CHANGE THE INITIAL ANGLE OF THE SHOT WHATSOEVER! OTHERWISE THIS OBVIOUSLY WON'T WORK). Hope this helps shave off a few seconds from your time as the traditional way of completing the hole requires you to wait for the ball to roll into the hole.