an automatic relay choice algo:

when posting, post to as much relays as possible, in the background.

when reading, choose 10 from relays where the follows of the user are posting.

make that 5 if mobile.

if user marks something as spam or mutes someone, look at which relay carried that. penalize that relay. if enough penalties: drop that relay from read list or make the notifications from that relay not so apparent. also move those notes coming from that relay down towards end of a list to make it less visible.

if a relay is dropped, find another to make it 10 again.