Users who actually click links in the document are clustered towards early openers? Share doc for two minutes, collect clicks, unshare to cut off spam reports.
I received a lot of spam share notifications on Google Drive, and there is no spam in the Shared with Me view in the app. I don't know what their game is, but this is happening. It also doesn't make sense that Google Drive doesn't remove the notification after the file is no longer shared with me.