Photojournalism is probably the most intense genre of photography. You generally don't have hours to set up to get all aspects of the image capture right. Quick decisions about light, composition, the best settings to use, mean there is a high likelihood of error that compromises the image capture.
When we setup for landscape and nature photography (still life), we tend to get lax in our ability to react to situations. Why is that? Isn't landscape photography basically the same as still life? Yes. And no.
This is because the best light (golden or magic hour) often lasts a short time--with the very best light lasting only a few minutes. I've found that while testing a new camera on a relaxing trip in Arizona or New Mexico; finding locations, setting up, and preparation can sometimes take hours. On the other hand, I've been caught a number of times where the lighting was perfect--there was a break in the clouds; or the sun or moon was in a perfect location, and I was forced to rush through camera settings for lens selection, ISO, bracketing, and most importantly, the composition itself.
Ansel Adams took one of his most famous photographs, "Moonrise, Hernandez, New Mexico" on a November afternoon in 1941. He describes that while driving north from Santa Fe on U.S. Route 84, he caught a glimpse of the moon rising over the mountains. He had only a brief moment to set up and skipped through much of his normally lengthy preparation. He relied on his vast experience (including his "Zone System"), instinct and skill in order to capture one of the most iconic photographs ever taken, and one that recently sold as the most expensive photographic print of all time.
So, while the composition is foremost in the photographer's mind, the knowledge of the optimum settings along with a high level of knowledge of the equipment being used, is critical to making the capture a success. Failure to do so often necessitates some heavy post-processing to save the image.
When I worked in the motion picture industry, one of the jokes that would be thrown around by DPs, ADs, and producers was, " Never mind, we'll just fix it in post."
It was said sarcastically.