The shape
Replication keeps copies of data on separate machines. Copies can improve read capacity and survive a machine failure, but they need a rule for accepting and observing writes.
The useful question
What does a successful write mean to a caller? Acknowledging one local copy is fast, while waiting for a quorum makes more copies agree before success is returned.
Stress test
Partition one replica from its peers. Read from both sides and compare the possible stale result with the possibility of rejecting a write.
Tradeoff
Stronger consistency can reduce availability during a network split. The right choice depends on whether stale data or an unavailable operation is more harmful.