to me , the answer is plain and simple,
since someone in the past made a personal choice to utilize what i assume is a gutter downstream of the panel you spoke of, IIRC, that limits you to 30 un-udjusted current carrying conductors and combined cmil not to exceed 20% cubic area of copper occupation
once upon a time i went down this rabbit hole to try and learn something because i purchased dividers that installed in my 8''x8'' trough, wireway, gutter or whatever you want to call it,, .
I asked many inspectors along the east coast the questions to prevent rework.
I asked, "if i have a full metal divider inside my 8''x8'' gutter, is is "permissable" treat that as two separate paths,,, never got an answer.
my application was 8''x8'' with full metal dividers with removable single cover on the horizontal plane wall mounted up high. you remove the side cover and your looking at two "shelves" so to speak all the way around the room in a "U" Shape.
my objective was to electrically separate my larger conductors from my smaller conductors within this room perimeter "U" shaped gutter.
I just felt like it was the right thing to do , the lower section was the smaller #6 and smaller wires while the top was for higher draw wiring upstream closer to the UT source. I felt like since heat rises, most heat would be on the larger wires and wanted that heat to get out quick, allowing the smaller wires to not be affected because they are in the lower tier of my wire gutter.
Every so often every 8', the electrician cut in K/0's with plugs of 2'' in size for use to "pass through" , up, along the cieling and out to far end loads.
terminology was my biggest learning hurdle, because you need to use the correct term when speaking the words to support your case on thsi box or gutter or trough or wire way or whatever it needs to be called.
