While publishing a content tree containing several sites, I wondered if the publish process goes down the list as it appears in the tree. For example, if I hit "publish item" on the content node below, does Sitecore first publish the entire Home page before starting Global Datasource, and then waiting for that to complete before starting Site A, etc?

It would make sense because you have to process in some order, but Sitecore has had reasons in the past for not doing things the way I expect.