On my default list the Owner group has edit access to the items. In that list.  Everyone else has read access.

The "Owner" runs a workflow which grants the user edit access to an individual (let's call him participant)  on the form using a Set Item Permissions in a workflow.   That all works great.

After an "expiration" period a workflow runs to remove the edit access to the participant.   I added a Set Item Permissions to Yes.    I assumed it would revert the item to the default list permissions.  To the contrary.  What it did was to keep the participant's edit access and removed all access for all other users.

What I had to do was to explicitly set the access as I wanted.   Set Item Permissions, Inherit permissions from parent = yes does not revert to the default list setting?   If not what the heck is its purpose?  Is there any way to revert to default list settings without  explicitly  setting them with Set Item Permissions?