Average Islands Scale - Not actually scaling islands to same scale?

I’m trying to UV unwrap some walls and wall segments, and I know that each wall has the same height and each of these curved arches has the same width, or at least the same width as it’s opposing faces. They’re all snapped and aligned and vertices in the same axis on each. When I have all of my islands laid out and I select everything and then hit ctrl-a…everything changes scale and does what looks like a correct adjustment…but then when I turn on vertex snap and start trying to line up the islands on top of each other so I can do a horizontally tiling pattern, I start to notice that they didn’t all scale to the same aspect.

In this screenshot the walls aren’t shown in my unwrap, but you can see the selection shows two groups of similar curved arch unwraps…the 4 larger arch sections should share a UV space and the 2 smaller arch sections should share a space. They’re identical, I’ve checked…but once I ctrl-a average island scale, they show up as all being different sizes, as you can see in this screenshot.

I’ve applied all transforms (except location) in object mode, so there’s no errant rotation or scale transforms applied. Is there a different or better way to scale all of my islands to match each other in world UV space? Am I missing some combination or tool to make this easier?

Here’s a bonus shot of my wall unwrap. I had to put the 2d cursor in the bottom corner, constrain to UV space, and snap the bottom left corners of each of my wall islands (3 groups in all) and then scale manually each one to line up as close as possible (using snap to pixels) to the top edge of the UV space (y:1)…all because ctrl-a doesn’t make everything scaled to the same scale factor.

I feel like the problematic operative word here is “average” I don’t want to average the scale, I want to equal the scale…and I fear there’s no way to do that in blender?

I was looking for some add-ons and I didn’t find anything really that references Island Scale…I did see UV Magic has a world scale function, but I couldn’t get it to do anything here.

I’m still struggling with this on many different models…There’s a paradigm shift between this and Max that I’m just not grasping…No matter what I do I cannot seem to get groups of identical structure mapped to the same texture space. Average Island scale doesn’t ever seem to give me an actual relation…and Smart UV project doesn’t always give me the squared projections I’d expect either…Am I supposed to maybe use pinning? Will pinning corners help square things for me?

UVMagic also has a copy/paste UV which will size the uv island accordingly. I use it a lot of window frames and such, very handy.

Awesome! That’s quite helpful actually! Now if only I could get nice consisent unwraps. Any tips or tools for that? Not being able to iterate through the unwrap algorithm more than once seems to be a pretty big limitation to me.