There’s no concept of ‘scan frequency’ in 7.9, because the only ‘source of truth’ for project resources is the gateway’s internal DB.
In 8.0, when resources moved to the filesystem, we put a system in place to watch the filesystem for changes to resources; if an external change is made, it’ll be detected and override the configuration the gateway has in memory. However, the scan frequency was fairly aggressive and could, on systems with many projects, consume a significant chunk of CPU.
As a result, in 8.1, we lowered the time to scan from a hardcoded default 10 seconds to a configurable 5 minute default rate. The ignition.conf parameter to change is -Dignition.projects.scanFrequency=10: 8.0 to 8.1 Upgrade Guide - Ignition User Manual 8.1 - Ignition Documentation