Does MSC_ATP_CUSTOM hook triggers for all the item in a sales order line irrespective of ATP enabled

Hi,

Does MSC_ATP_CUSTOM hook triggers for all the item in a sales order line irrespective of ATP enabled item at the  time of unscheduling?

Currently we are using MSC_ATP_CUSTOM.CUSTOM_POST_ATP_API to trigger custom logic at the time of SCHEDULING and UNSCHEDULING.

At the time of Scheduling MSC_ATP_CUSTOM is triggered only for ATP Enabled item, but at the time of UNSCHEDULING the same hook is triggering for NON ATP Enabled item as well.

My question is, is this the standard functionality (i.e.) at the time unscheduling MSC_ATP_CUSTOM will be triggered for all the items irrespective of ATP Enabled or NON ATP Enabled.