Agreed - different buddies can bring different things to dives. I have gone out a fair bit with groups from the same dive shop but been buddied with different people and it is good to pick things up from them both in conversation and by observation.I started diving all alone and find myself in a very good group. That was my luck. I dived with them with several different buddies. Diving with the same buddy is comfortable, diving with different buddies is experimental. It teaches you a lot. This year my wife started to dive also. During her first dives I was always her buddy or her tail. But after some dives I refused to be her buddy and said her to dive without me. At first it is very good to dive with an experienced diver whom you trust but if she dives only with me, she will be my follower which slows her learning process dramatically. Today sometimes we dive together but mostly she dives with other buddies and she is learning something from all of her different buddies.
Short version J Don’t worry to dive with different buddies, it is much better for you.
I think some of the best advice I would give to someone starting is to be a critical diver - watch what you, your buddy and other groups are doing and learn from it.
Is your buddy all over the place with buoyancy and trim? My first post cert buddy was and I made the point of "I am not going to be that diver" so concentrated a whole lot more on those aspects. Similarly if your buddy is really good, watch them or ask questions of them - they might be able to give you good pointers.