Certainly a fair question. As with many things, it depends on many factors and details. But I think it is fair to say this: when soloing the dangers are about the same but the consequences are more grave. Twisting an ankle while solo, versus the same injury when in a group has very different potential costs.

I used to do a lot of roped solo rock climbing up to about 5.9 and A3+. The moves were what they were, but the potential cost of taking a fall was higher. It made me think very thoroughly at every juncture.

The upside is that after soloing the rock or the trail, going with a partner felt like cheating.