song writing and arrangement process

So from what I gather, the songs are often started by Michael on his acoustic guitar in his office just finding chords that hit him the right way. But does anyone know how exactly they go about making these arrangements that flow so organic? Like Im thinking of tracks like Cloud of Unknowing, Glowing Man, Avatar etc.

I've heard interviews where the members said that for recording My father will guide me... that they didnt even have any time to rehearse and just went into the studio, Michael had given them some files of him playing acoustic, and they just went in developed parts for a few hours then went in and tracked, doing that each day for each song.

Is that actually what they do??? Does that mean that Michael likely arranges the entire song on acoustic before hand ? Like for instances all those different movements in a track like Cloud of Unknowing, would he just structure out those on acoustic?

If that is the case, from a musical perspective that seems very strange as so many of those parts feel like they require the various instrumental textures to give them their essential energy and so it would seem more like they are things that would emerge organically out of jamming...

If anyone has any insight into how this sort of song construction may take place please share as it could create an interesting discussion.