MacOS – How to get right-size this column to show entire filename

I was so sick of this, so I decided to write a fix once and for all.

You can use the following AppleScript to resize the column widths when you notice the column is too wide. It works by resizing the Finder window really large, then back to it's original size, triggering a fluid layout resize.

tell application "Finder"
  tell the front Finder window
    -- get the current bounds of the finder window
    set b to the bounds
    -- create a really wide window
    set the bounds to {item 1 of b, item 2 of b, 3000, item 4 of b}
    -- set window back to its original size
    set the bounds to b
  end tell
end tell

This will probably be most useful if bound to a keyboard shortcut, I personally bound it to CMD + E using BetterTouch Tool.

If you're after more detailed information regarding this, you can head over to my blog post about it here: https://christianvarga.com/fix-finder-name-column-width-bug-osx-mavericks/

Actually, the solution in your linked question still works as of 10.11.6 - I think your issue is you are confusing Column View & List View... based on your stating '"Name" column', which column view doesn't have.

For List View, just drag the column header divider.
To make it default, Cmd ⌘ J & Click 'Use as Defaults'.

I am uncertain as to whether that will override any existing ._DS_Store setting for other windows - you may need to clear them if you want to start afresh with your new defaults.