I played it this way as well. If I said I was going out on a day other than "the group ride" Mercury (Hg) was there. He was part of the reason I was going out and I was clear on the route /distance with him in mind (in his prime 16k was the sweet spot). If some one said otherwise "Well have a good ride then...." Until he was 8, Hg often lead all but the fastest and longest of descents. He would get invited on rides too, the tone is set then. He did come on the odd group ride nite too (if it was the right route), but never w/ out a check in. Often those were "pack rides" anyhow, and he had company.
He was, and still is the most annoying creature to drive to a trailhead with. Even at 10 yrs old and over a thousand trail days. The thought of shuttling with him..... NOPE. Gets as amped for his 4-5 km walk and sniff in the local woods as he ever did for big adventure laps in places like Revelstoke.