The longer the ride, the more I prefer group. Faster, less likely to get lost because someone will always be more familiar with a given area, more eyes to watch the bikes during breaks for food or facilities. Even a helping gulp of water or food if I fail to carry enough.
I've ridden exclusively solo or indoors since last March and I've struggled to decide where to ride outside when the weather's good. Every outing, I've encountered an unexpected and poorly detoured road closure. Riding out of my familiar zone is a necessity since I live in the city and there are too many stops everywhere, so it's inevitable that I end up perplexed when going solo.