Ok so planman is kind of your automation tool to push scheduled jobs in BigFix but Repeatedly sending Force Refresh commands to clients, regardless of conditions, can lead to significant issues over time,
Force Refresh command instructs the BigFix client on endpoints to immediately re-evaluate its relevance, re-send its current status to the BigFix server, and reapply relevant actions. Issuing Force Refresh commands to a large number of clients simultaneously can lead to several problems like network spikes, server overload, client performance impact, interference with normal client operations.
You must coordinate with the administrator of your Planman tool and request that they schedule the actions ahead of the maintenance window, maintaining the start and end times in accordance with the actual deployment window.
I’m not sure what strategy Planman is using, but if they are using XML Push to schedule an action, they must update the fields below before using XML Push.
<HasStartTime>true</HasStartTime>
<StartDateTimeLocalOffset>**Desired Timing**</StartDateTimeLocalOffset>
<HasEndTime>true</HasEndTime>
<EndDateTimeLocalOffset>**Desired Timing**</EndDateTimeLocalOffset>
In case of issue with start/end time calculation, you can take reference from below post.