In the new versions of blender (2.9, 3.0, etc.) you can do it in Video Editing layout without any modifiers, simply by changing the Strobe parameter in the strip's options:
Maybe my answer will help someone. Hope so :)
you can still save it here:
I am using a mac so i don't know your shortcut, but you can see it right beside the menu entry.
The default shortcut for it is ALT + S. Shortcuts are Area specific so make sure you hover on the image when pressing this.