It would also matter how many people were shared between the relays. The influence of that will go down as relay content specializes in the future.
Discussion
Indeed.
If I follow a total of 100 people and only 10 of those have write permissions to the AmConf relay then 2 things are true:
1.) I'm already getting notes from those 10 people regardless of whether or not I am subscribed to AmConf relay
2.) You most likely figured out why my theory doesn't hold much water. At least in the Local feed view. Global, I think, would be changed.
What if we had Local, Global, and Federated (Subscription) feeds?