If true (default), only projects that are new or changed since the previous run are delivered and charged. If false, the full filtered snapshot is delivered every run, but only new/changed projects are still charged. Uses a shared, persistent key-value store snapshot ('uk-bess-repd-tracker-snapshot') that is also read and updated by scheduled monitoring runs, not just this one. On the very first call ever (no snapshot exists yet), there is nothing to compare against: every project in the filtered set is treated as new, so the entire filtered snapshot is delivered and charged that first time regardless of this setting.