On easy trails, large club events are a lot of fun. I get personal enjoyment out of seeing newbs learn the ropes and watching their rigs and driving skill develop over time. Gives me opportunities to get out of the cab, relax, take pictures, bullshit with friends, and take in the sights. When I blast through these easier trails with small groups of capable Jeeps, I don't really get to see much of the trail because I'm concentrating on driving the whole time. Many of my most memorable and fun runs were large club runs. These runs generally aren't hard enough to be ruined by the guy running 37s on his D35 and insisting it can do anything a D60 can do, or the "I can run anything without lockers" guy.
On really difficult trails, large groups can be a PITA, especially considering that folks in under-built rigs and inexperienced drivers will always insist on going. these runs often turn into nightmares of overnight recoveries, beating up your own rig pulling the under-built rigs through, exhaustion from hours of stacking rocks, and the frustration of dealing with the "D35 guy's" pissed off attitude as he tears his shit up - which in turn pisses off the other people working their asses off trying to get him through the trail. As I grow older and wiser, I try to keep the difficult trails runs to small groups of people whos experience and rig are up to the task.