If you’ve never listened to Blackberry Jams, it’s a great compilation of unfinished versions of mainly his Perpetual Burn material where many of the songs aren’t fully arranged and you can listen through the entire album and pick out where one song became two entirely different songs and fused with parts of others.
Strongly recommend going through this as an example of how building up a body of material and rearranging it into a finished album can work.
One example - part of this ends up in altitudes, part ends up in Temple of the Absurd: