I occassionally ride alone. But with 4 horses needing exercise, I try to fill the saddles if I can. If my daughter don't want to come, then I get a neighbor or friend. Not because I'm afraid to ride alone, but because I need to exercise all 4 horses.
Often in the fall for hunting season, I often ride into camp by myself. Sometimes my friends have arrived earlier than I and sometimes they come a day or two later. And we of course usually split up and hunt by ourselves during the day, So I am riding by myself a lot during the hunt. So it's good to ride alone during the summer to teach the horses that it's OK to be alone and not be herd bound.