I have noticed that my mood not only can affect how I write but also what I'm willing to write about. For certain types of posts you need a certain state of mind.
Sure, with my experience and practice I could technically wtite about anything at any time. At least I like to believe so. That would however probably result in a post I wouldn't be happy about. A forced text where I didn't give all the effort the topic deserves.
Writing isn't either only about producing text. It can also be a tool to organize your thoughts or even means for thinking itself. And if you are not in the mood of thinking something it's just not going to work.
So if I really want to write about something specific should I rather wait until I'm in a correct mood, postpone the topic for later time and write about something else for now or try to get to the right mood and have it dealt with right now?
The second option is the easiest one. There is always something to write about. But will that right time ever come and do I still remember then the topic and the intention to write? The first one could lead to a panic post when the mood doesn't come but the night will.