Block time can mean a protocol's target interval, a scheduled opportunity to produce a block, or an average measured from actual blocks. Those are different quantities. Bitcoin adjusts mining difficulty toward a target average interval, while individual proof-of-work discoveries remain irregular. Ethereum's proof-of-stake design organizes opportunities into slots; an unfilled slot does not create an execution block merely because its scheduled time passed. Clear statistics identify which quantity is being reported.

Suppose a sample contains blocks observed at seconds 0, 8, 20, and 44. The three intervals are 8, 12, and 24 seconds, so the observed mean interval is about 14.67 seconds. Dividing the full span by four blocks would answer the wrong calculation because four timestamps contain three gaps. A short sample can also differ substantially from a longer one. This example illustrates measurement; it is not a claimed interval for any particular live network.

A lower interval can improve how quickly a transaction first appears, but initial inclusion and durable settlement are distinct. Throughput also depends on block resource limits and transaction complexity. Comparing networks only by their advertised block time hides these factors, as well as missed proposals and reorganizations. A reader evaluating a payment flow should separately ask about typical inclusion latency, variation during congestion, and the network's finality mechanism. A fixed schedule cannot guarantee that a particular transaction will be accepted in the next opportunity.