Critical high-level stats such as errors should be scraped more frequently than 30 seconds. It’s important to have multiple time granularity scraping intervals, a small set of most critical stats should be scraped closer to 10s or 15s.
Prometheus has as an unaddressed flaw [0], where rate functions must be at least 2x the scrape interval. This means that if you scrape at 30s intervals, your rate charts won’t reflect the change until a minute after.