desktop-file-install for all desktop files?

[Christoph Wickert]

Do we need desktop-file-install for _ALL_ *.desktop files?

I'm NOT talking about files under 

        /usr/share/applications

but about

        /etc/xde/autostart
        /usr/share/gnome/autostart/
        /usr/share/Terminal/apps/
        /usr/share/Thunar/sendto/
        /usr/share/xfce4/helpers/
        /usr/share/xsessions

to name a few. The reason for me to ask is 
https://bugzilla.redhat.com/219986 ,
https://bugzilla.redhat.com/219990 and all my xfce4-panel-plugins, which
drop a desktop file in /usr/share/xfce4/panel-plugins. This file is
needed for the "Add Items to the Panel"-dialog in XFCE. These desktop
files don't need to be changed (e. g. --add-category=...) and cannot be
edited like the main menu.

>From the guidelines at 
http://fedoraproject.org/wiki/Packaging/Guidelines#head-254ddf07aae20a23ced8cecc219d8f73926e9755
"This is mostly for the sake of menu-editing (which bases off
of .desktop file/path names)."

So am I correct that we don't need desktop-file-install for desktop
files that do not show up in the menu?

Christoph