Rudder

The agent uses the ScheduledTask "RandomDelay" feature, but this is recalculated for each run, and so, the agent does not run every "AGENT_RUN_INTERVAL" but every "AGENT_RUN_INTERVAL" +- a random minutes delay between 0 and "AGENT_RUN_SPLAYTIME".
To keep the startime spray and re-enable the agent run periodicity, the best solution seem to let the webapp generates a starting hours/minutes/seconds calculated from the node uuid and the node settings which should look like:
"00:00:00" + "First run time" (taken from settings) + random(0, "Maximum delay" from setting)

The computed value should be added to the rudder.json generated in the policies for each node, under a key named "AGENT_RUN_STARTTIME" and with a value following the format: "HH:MM:SS".