What's with the drop in speed etc. about every 10 minutes? I enjoy a nice 4-6 person rotating paceline, but I like them better when well warmed up. They're usually over/under intervals, very good at improving the ability to clear lactate. When I come to the front it's like getting hit with a fire hose. I notice a big difference, dying until the next guy pulls off in front of me. It's a training ride, not a pleasure ride. I sure wouldn't want all my group rides to be like that, just like I wouldn't want to only do over/unders. I enjoy climbing, descending, attacking, covering, bridging, pulling, all that group ride stuff. Makes my solo rides seem very dull.
Group rides come in many flavors. I enjoy them all. I like the cameraderie, the heightened awareness, the speed, and the general social aspect once one gets to know the usual participants. My take on group rides is that it's like being out with a primitive hunting party, all of us running. I see small dog, call "lower lances".