You’ve probably heard the metaphor.
If you have a container, and you have some sand, pebbles, and big rocks, what order should you add them in order to get the most material into the container?
If you add the sand first, there won’t be any room for the rocks. If you start with the pebbles, you can fill in the crevices with sand, but there won’t be any room for the big rocks.
But if you put the big rocks in first, then you can add the pebbles, and then the sand, to …