More relays = access to more notes but also more bandwidth usage
The only conflict of interest I can think of right now is: If a relay starts censoring mass exodus to other relays will follow
Discussion
How much bandwidth are we talking exactly
The thing about bandwidth is that it exists at both ends of the connection.
So whilst a client might follow
A relay might be serving 5,000 clients.
User traffic = [y] follows * [z] relays
Network traffic = sum ( [x] users )
Unfortunately I don’t know how much. However, more relays = more data is pulled = more bandwidth usage.
Yes, I think you query every relay you list, for every one of your follows.
So data = follows * relays
It’s likely to be fairly linear.
A smarter client might rank relays for responsiveness and truncate it’s use of weaker relays (maybe they are just far away?).