A push-based price feed may publish when a price changes sufficiently or when a heartbeat interval elapses. These are different triggers: a quiet market may still receive periodic reports, while a fast market may receive updates before the interval expires. Chainlink documents feed-specific heartbeat and deviation settings. The timestamp of the latest accepted answer is therefore as important to an application as the numeric answer itself.

Imagine collateral last reported at 100 while its venue price falls to 90. If the consuming application continues to accept the older observation, it may allow borrowing based on an outdated valuation. A freshness check can reject a report older than the application's tolerance, but that tolerance must reflect the feed, market, and chain. An overly strict rule can also halt otherwise valid operations when reporting or transaction inclusion is delayed.

A heartbeat is an update configuration, not an unconditional guarantee of an on-chain transaction every exact number of seconds. Chain congestion, feed outages, market closures, and application-specific adapters affect what a consumer receives. Review timestamp handling, decimal scaling, supported trading hours, fallback behavior, and any layer-two sequencer checks. Treating every feed as if it were a continuously traded crypto pair can produce incorrect conclusions for foreign exchange, commodities, or other assets with different market structures.