There is "no" configurable collection schedule for the following alarms.
Monitored Server - Windows Connection Failure
Monitored Server - SQL Server Connection Failure
If you go to "Configure | Scheduling," there are no options to alter the interval or frequency of collection. These alarms aren't raised by a scheduled collection; they work a different way. Any collection that fails due to what Spotlight consider is a connection issue will cause these alarms to be raised.
Of the two, only the Windows connection does 3 retries before raising a connection failure alarm.