I want to show you a couple of great tree painters so that you can look at the restrained and simplified way each of them approached the sky hole problem. The painting above is by John Constable, courtesy of the artrenewal.org. Look at how "big" he kept the shapes in those trees. The sky holes are kept to a minimum and the large forms are dominant over them.When you see it done, it seems no big deal, but when you are confronted in nature by a tree with dozens of holes in it, some hard decisions have to be made.
The next painting is a Corot, look how few sky holes he used, just a handful, and they are carefully placed to both look random and to reveal the shape of the tree. Notice how airy those trees are, their wispy handling makes them look ephemeral. Their beauty is in their delicacy.
Here is more delicacy., this John Carlson is full of soft passages and artfully arranged shapes. The top third of this painting is an arrangement of unique and interesting shapes. These were designed carefully to be both random looking and to carry a concealed rhythmic geometry. Notice how differently each of these painters has handled the similar problems in their paintings.