On Tuesday,  6 Mar 2018 at 22:15, Shérab wrote:

[...]

> I am fine with steps 1 to 3 but would like to do steps 4 to 8 in a much
> more efficient way, without having to re-enter the date, but with the
> same result,i.e. the heading being added atthe endo of ~/gtd/agenda.org
>
> Do I make more sense this time?

Yes.  And my original response is what you want.

Set org-agenda-diary-file to "~/gtd/agenda.org".  Then, from within the
agenda view, if you type "i d", you will be creating a new agenda entry
for the day you are looking at.  That's steps 4 to 8 in a nutshell.

-- 
Eric S Fraga via Emacs 27.0.50, Org release_9.1.6-191-g90607d