Currently, Alteryx Server has a setting for how many days to keep Results from scheduled workflows, which prevents your Results log from getting too large.
Unfortunately, this setting is universal to all workflows, regardless of schedule. If you have monthly jobs sharing a server with jobs that run every 5 minutes (which we currently do), and you set your limit to 30 days, you get at most 1 result from monthly jobs, but 8,640 results from your 5-minute jobs!
A better option would be to keep the most recent X results from any schedule (where X is user-configurable).