The photographer who is unable to adjust to the day is only a photographer in fair weather. In every profession, you could restrict yourself to days in which conditions are correct for you to engage in an activity. You might only write when inspiration strikes, or produce art only when you have a feeling. The problem is when you cease to create because one or two conditions are not met. The photographer who has a bad lighting day must learn to adjust and continue to take pictures. The pictures should turn out just as they would have because of the photographer’s ability to improvise and find solutions to problems.
That is the ability you should strive to cultivate: have so much skill that circumstance doesn’t restrict you from continuing to work. From Steven Pressfield in The War of Art, you learned to write only when inspiration strikes…and “inspiration strikes every single morning, at nine o’clock sharp.”*
*That’s a quote from Somerset Maugham mentioned in The War of Art.