For sighting in or testing loads, I prefer to shoot alone so that I can concentrate and not feel rushed.
When shooting clay pigeons, I prefer to be with friends as it is fun to have others to leisurely compete with. Also, it helps having others to launch the pigeons.
When shooting my fun guns (non-hunting guns, military surplus guns, and pistols), it depends on my mood. When I’m with someone, I enjoy the sense of letting others use my guns and seeing their satisfaction in playing with a new “toy.” When I’m alone, it’s enjoyable because I can concentrate, work on skills, and try new things.