I create my first time based workflow to run every 15 minutes.
But in practice it run every hour!
My vtigercron.php schedule to run every 15 minutes, and it run every 15 minutes.
I know that beacuse my "Mail Converter" working fine every 15 minutes.
In: Cron Tasks Scheduler: Cron jon workflow is set to 00:15
probably not every hour, but every half hour is possible.
this works like this: when the workflow scheduler launches, every 15min, it looks to see what workflow tasks and scheduled workflows have passed and executes them. Now, imagine that the scheduled workflow is triggered and takes a minute or so to finish. The next time the workflow launcher runs, 15min have passed but for the scheduled workflow it has been only 14min, so it isn't executed and has to wait another 15min for the workflow launcher to run again, effectively being 30min more or less.
In short, you need to set the workflow launcher to a lower frequency than the least scheduled workflow frequency or you may have cases where they sync doubling the time.
