New Relic uses custom events to track and analyze its own systems, with over 30% of telemetry data being custom events, compared to only 5% for typical customers. Custom events are schemaless and can be created at any time without advance registration, allowing users to record specific data points such as file uploads or modifications. This enables experimentation and data-driven decision-making, as well as performance benefits due to the smaller number of custom events compared to more generic types like spans and transactions. Unlike logs, custom events allow for direct recording of structured data in a format that can be easily queried using NRQL.