What counts as an unbroken open space for 2D wall spells?

[Supe]

So a play group recently had a dispute on what are valid placements for spells like Wall of Force and Wall of Ice. We are aware you can't cut through creatures or objects, but there was some hangup on what an "unbroken open space" is. Are you able to place to flat walls on edges, or can they only be placed through the middle of actual grid spaces regardless of the wall's width?

The main concern is: are you able to "divide" a battlefield between two adjacent non-diagonal creatures using wall of force, or is that functionality only for Wall of Stone? What about dividing creatures in the diagonal direction?

Specifically, which configurations are valid in the image below:
https://imgur.com/a/Upvht8Z

No matter how I interpret it, it appears to be legal to separate creatures diagonally, but horizontally is where it gets iffy. Currently, the two interpretations of "unbroken open space" I've identified are the general one (do I have space for this TV) or open grid spaces.

[Finoan]

My opinion on this is that it should be handled by the players at the table for each scenario. I don't think there is a 'one right answer' at all.

Ultimately the rules are there to support telling the story. Not as shackles to prevent players from doing things - unless those things are going to be disruptive and negative to other players (including the GM as a player at the table).

[Supe]

I was hoping for a not rule zero answer but I suppose it be what it be. Having it be "fills grid squares" or "anywhere a wall could fit" are very different in terms of performance and balance though that do what you want, despite it being a fallback for anything, isn't very ideal in this scenario.

For what its worth, most interpretations online seem to be that a wall can go anywhere so long as there's room for it. But I can't really use this as verification for anything.

[Gortle]

Supe wrote:

Specifically, which configurations are valid in the image below:
https://imgur.com/a/Upvht8Z

I am happy with all of those personally.

Walls occur on the intersection of lines.
So it seems clear enough to me.