I often use an SB-5000 or SB-500 for fill, even for casual stuff and almost always for landscapes. I also use various light-shaping products so I can use the additional light to highlight a specific feature. Depending on the situation, I may reduce the power to "underfill," which makes the additional light less obvious. In a bright sun situation, I will do the opposite and "overfill" to overcome the deep shadows caused by the sun.
I should note that I've been shooting with fill flash for close to 60 years, dating back to my days as a news photographer, and I tend to view every photo as needing a bit of fill
Just habit, but I get compliments from magazine editors because of the extra "snap." The SB-5000 is awkward to carry, and I prefer the SB-500 and would like something even smaller but the flash sync on the Z9 isn't compatible with many flash units :-(
[About a zillion years ago I took apart a Honeywell flash and rebuilt it into a much smaller footprint (and less light), which made it easy to keep on the camera all the time and was perfect fill when shooting Tri-X at higher ISOs. I miss that flash because it was innocuous and didn't interfere with the handling of the camera. Since then I've wished for a "flash cube." (One was briefly available a long time ago, but I can't remember who made it.)]