So basically using one of them to read global is enough?
Discussion
I would still use a few other relays, since they're not necessarily syncing with every relay out there
Just to be clear strfry instances don’t automatically sync or stream to each other, it’s up to the relay operator to choose if they want to use any of these tools and with what other relays.
Of the list I can only say for sure that filter.nostr.wine is doing aggregation or broadcasting but no idea about other relay operators.