R G, No sense to blow yourself up trying to keep up with a group. Shortly after I started riding again after my knee injury I dropped off the back of a group on a shortish ride to just ride at my own pace. A little later I caught up with another rider who'd dropped and he was a mess physically because he severely overexerted himself trying to keep up. We hadn't reached mid point so I rode with him back to the cars.
Bottom line is I'd just continue riding and not worry about the group. Exploring is a lot of fun though it might lead to you becoming an expert at U-turns
. Remember that first and foremost cycling is fun. Yes there are training rides where fun isn't a factor, but an improved cyclist is the goal and at the end of the training ride you should still feel good about having been riding.
Maybe it's just me, but until I get the first thirty minutes or so on the bike, I'm not going to try and gun down anyone or play catch up. I like the idea of getting everything 'up to temp', whether it makes a difference or not, I really don't know.
Brad