Grace Period is an optional feature that captures updates and notifications to variable fields even after the scheduled time. If a field is modified within the given grace period window, the event will still send.
This can be set to while setting up Time of Day of scheduling.
With grace period:
If the touchpoint is scheduled with a grace period of one hour with an actual time of 10:00 AM. If the candidate is added to the audience before 11:00 Am will also get the touchpoint.
Without Grace period:
If the touchpoint is scheduled without a grace period of one hour then any candidate added to the audience after 10:00 AM will not get touchpoint.