5 is plenty, if you're using the right 5.

1. a blastr relay like wss://nostr.mutinywallet.com

write only, but publishes to dozens of the top relays.

2. an aggregator - nostr.band, nostr.lol, others

read many many relays with one connection

3. DM considerations. I don't get DMs from some folks unless I'm using the exact same relay. The aggregators don't seem to do those.