Please take some effort into trying to make clear what the confusion is for you.
false --> It is recommended and simpler to add the new year to all files in the package, and be done with it for the rest of the year. That is what the GNU Coding Standards say, so it clearly is not "false". If you add a new file, from a different project, which was not updated this year, then you would add 2018 in your new copy of that file. Adding a new file is a signitificant enough modification that it would warrant updating the copyright years for _all_ files in the project; including newly added ones.
