Late starts, trains, and junk miles

For the second Saturday in a row I got to do the Mad Duck ride. Thanks to my wonderful wife I got to go out for a few hours and enjoy riding. Not only was she ok with me riding while she took care of Connor but she is the only reason I woke up in time to make it. I had set my alarm for 6am but apparently turned it off with out actually waking up. She woke me up at 6:30 and ask me if I was skipping the ride due to being up longer last night with Connor. Once I woke up enough to realize that I could still make it to the ride if I hurried I got up had breakfast, espresso, and was out the door.

I had a great ride but given my lack of fitness got dropped from the group twice (It is always nice to find short cuts). When I was trying to chase back on to a group I got caught by a train. Sure a train is nice when it stops the group you are trying to chase but not so nice when the group gets through and you don't. While I was sitting and waiting for the train to pass I started thinking about how I had been riding between times I was with the group.

When I am with the group I don't mind riding as hard or easy as the group is riding and so I don't really pay much attention to staying within a certain heart rate zone. At least that is true with my Saturday ride. Other rides I do a better job staying where I need to be for training. However, when I was taking short cuts to get back with the group I was riding hard but not super hard. I was in a "comfortable" zone 3. Standard junk miles. It worked to let me get back to the group but I started wondering about the impact/ effectiveness of the ride on my overall fitness. Now I am not racing now but I do want to make some progress regarding my form and being able to stay with the groups. I rationalized that I was doing what I needed to so that I could get back to the group and stay with them a little longer. However I did ride like that for 45 minutes or so before I was with them again.

So I guess I want some advice/opinions/critiques. Once you are dropped from a group like that is it better to do what you need to so you can rejoin the group OR is it better to go to either base ride mode or do intervals? Granted I am just trying to regain some fitness but if I can get into racing shape I would be very happy.

So if anyone has any thoughts let me know.