I tend to think that one of the challenging elements that emerges from the film is that there is a blurring of the lines between what is considered to be "major" and what is considered to be "minor" in the mind of the artist conscious only of themselves and the relationship to their work.
Charlie's entire being lies at both the questioning of his identity as well as that of his work. Everything is major, in this light. What breakfast he wishes to have becomes significant. How much he will work and his workout routine are all minor issues, but they hold significance.
The reason for this is Kaufman's premise that the artist and their work are inseparable. Choices made in one realm are directly reflective of the choices made in the other realm. "We are what we love" becomes the basic mantra of being at the most critical of moments. In this, all of our choices, regardless of scale, becomes a reflection of who we are and in what we place importance.
When an artist makes a choice to define themselves in a particular manner, this value set emanates in the work, also. I believe that this is why everything becomes of relevance in the film. The film's premise demands that all elements of being are taken into account.
Muffins, as well as the formation of the planet and all of its life forms converge in the mind of the artist who wishes to stay true to both their work and themselves. In this, there can be little traditional distillation between what is major and minor in the mind of the artist.