The problem is that the write buffer turns copy progress into a complete lie. The last time I put a large file on a removable drive from Linux, the copy finished suspiciously fast. But I thought that surely Linux wouldn't be using a write buffer when Windows hasn't used that on removable devices for 20 years, so I went on my way and shut down the computer... which led to me just sitting at a gray screen. I had to just wait there with no indication of progress or even that it was doing anything at all.

If I wasn't aware of what was happening here I likely would have just force shut down the computer after a minute of waiting. And I suspect if I had done that and checked the drive it would have appeared like the file was there, while actually missing part of the data.

I did some digging and found:

1. Arch uses the "flush" mount option by default when using udisks (which is how removable devices are mounted interactively from a DE).

2. Manjaro has a package called "udev-usb-sync" that matches USB devices in udev and limits the write-buffer size. However, it appears to (by default, you can instead specify a constant value) calculate the buffer size based on the USB transfer speed, and given the fact that I have some USB 3.1 devices that cannot maintain 1MB/s of throughput while others that can maintain over 200MB/s of throughput and both report the same transfer speed to Linux, I don't know how effective it is.