I ride alone at least 95% of the time, and the other 5% are generally times I've gotten there and run into some folks at the trailhead so I join in with them. I like the quiet, and I like being able to speed up or slow down at my own pace. I've ridden in groups on the road that are fine, but it takes a lot of effort. Not that I don't want to be social, but people sometimes drive me crazy.

We have a dry erase board on the refrigerator at the house. I always write down which trailhead I'm parking at and what trails I intend to ride by the end of the day, in order if I can. It may look like this --

Campground trailhead -- park
Trail #1 - 1 hour
Trail #2 - 30 minutes
Trail #3 or #4 - 1 hour
Back to trailhead on gravel camp road - 15 minutes

It may be overdoing it, but I have also used to go run on the same trails. A few years back I didn't have to be at work until afternoon. I dropped my kid off at school and drove straight to the trailhead. Completely forgot to tell anyone other than my son where I was going, and my wife and other son were out of town. 2 miles out into the woods I fell. Rolled down the hill. Busted my phone to pieces (and there was no service either way). Cut up my arms and legs and was pretty sore, but I jogged the 2 miles back to the car and made it in to work about 10 minutes late. It scared me a bit, so I started writing it down.