When fixing schedules, any feed with the fetch_interval_secs attribute to nil will have it set to the default value of 1 hour.

Also when adding the missing update schedule for a feed that has never been fetched (last_fetched attribute to nil), the first fetch is scheduled to run at a random time during the next hour. This kickstarts the update process and spreads feed updates randomly over time, so that jobs run at more or less evenly spaced intervals.