Is it useless to have icon sizes other than 32 & 256 in Win11 on the desktop?

Just moving to Win11 now, as there's no compelling reason to do so. Anyway, I have a lot of custom icons I like to replace standard Windows stuff with, so I deployed my first one to the Recycle Bin today. I have a full suite of sizes in the relevant (single) *.ico file, 16/24/32/48/64/128/256, but Win11 is doing a terrible job of using them. As I change resolution back and forth to test the issue, in fact, the OS seems fixated on 256x256 and 32x32 and doesn't want to use any of the other sizes. After some random size changes where it stayed with the 256x256 version even as I went down to about half my monitor's capability, the ultimate test was when I took the monitor down to its very lowest resolution, 800x600, scale set to 100%, desktop preference set to small icons, and it still only went down to 32x32. Not 24x24, let alone 16x16. I know those are usually taskbar icons, but still--800x600 with preference to small? Holy cow. Right now I switched it to 1280x1024, still 100% scale, set to medium icons, for which you'd think it would use 32x32 or maybe 48x48, but nope, it even jumped over the 64x64 and is using either 128x128 or 256x256 (can't tell which of those; image is compressed too small) and drastically scaling the image down. And this behavior is not some random screwup that will be solved by a restart, because I DID restart--and it's still doing it.

So I'm coming to the conclusion that in Windows 11, if creating custom icons you might as well just do a 32x32 and a 256x256 unless you know for sure you're going to use the icon on the taskbar or toolbars. Or is my experience anomalous? I'm jumping straight from Win7 to Win11, so I have no idea how 8-10 did with icons, but Win7 certainly used sizes more fluently.