Is it better to fill your first draft with excessive detail and edit the unneeded parts out after or if it is better to write simply and go back and add in the details after it is done?
That's a personal writing preference. Very much however it works best for you. I've done both.
These are the questions I would be asking:
Which is faster? Which is better creatively for me as a writer?
You also need to ask yourself, and be honest: how brutal can you be when you need to cut your detailed work? Is it easier for you, emotionally and artistically, to add in content or cut it?
If it interests you, this have been the subject of researches, notably by french literary theorist and semiotician Roland Barthes (in Introduction to the Structural Analysis of Narratives)
Barthes divide writers in two categories :
Ellipsis writers : (sorry, not sure of the exact term), such as Flaubert, who will write an extended first draft (or many versions of the same text or dialog) and then cut into it.
So, that's the category which write "Excessive detail and edit the unneeded parts"
Catalysis writers : Like Marcel Proust, who will write a first draft and then add extensions to the text (Look for Paperolles de Proust on Google images)
Wich correspond to filling with details afterward. Barthes tried to find the semiotic significance of both practices, and it's really interesting, if a little bit of theory don't repel you (basically it's about the ways a writer will formulate what he's trying to say)
I would just like to add that it's not about the necessity of those details, but about the moment you will like to add them
Sometimes you need to write many versions or an extended draft to decide which part will really serve your narration (or just because you want to follow you imagination with the Edit Demon shut off), but then your text can become muddy, that's what I was used of, and that's why I tend (or try) to get closer to the second category : writing a simple first draft (of a single chapter for example) with a clear structure that will contain all the basics of my narrative unit, without additional details, like a skeleton, and then flesh it out with all what needs to be developed.
I can't see why, at time of writing, you would ever include a detail that did not seem apt and necessary at the time. Nor can I see why you would ever omit a detail that did seem apt and necessary.
It is quite likely that you will decide later that many of the details you thought apt and necessary are either not apt or not necessary or both. You will remove them. And you will also discover that other details are apt and necessary. You will add them. That is what revision is for.
But I can't see why you would plan to say too much or too little in the first draft. The first is a waste and a distraction and the second risks losing the inspiration that allowed you to imagine the scene.
Write as much or as little detail as seems apt to you in the moment. Whether it is too much or too little is something you will discover later in revision.