Here is the reference in the documentation:
When a campaign is executed, the counts are cleared on all of the nodes in the campaign. A single job is executed. This opens a single copy of the campaign with Write access.
When an individual communication is executed, the counts on the nodes that are upstream from the Communication node might not be cleared. The clearing of counts on the upstream nodes depends on whether Use the most current data when executing communications is selected on the Campaign Properties page. For more information, see Specify Campaign Properties. One job is executed for each communication. During execution, each communication opens a copy of the campaign with Write access.
Have a great day!
From <https://go.documentation.sas.com/doc/en/cicdc/6.6/macdc/maug/p04wx3jvstpua2n1g6q6jumnq7ix.htm#p0pczw...>