alt Hacker Newshow many thousands? I have a folder with a total of 12760 files spread within several folders, but the largest I think is the one with 3827 files.
I've noticed the sync isn't instantaneous, but if I ping one device from the other, it starts immediately. I think Android has some kind of network related sleep somewhere, since the two nixos ones just sync immediately.
I have around 4000 photos and videos in this folder. I don't know what it is but I know that it's not a network issue.
I think it takes a long time because the phone CPU is much slower than the desktop but I couldn't tell you what it's doing, the status doesn't say anything useful except noting that files are out of sync and that the other device is connected.