More realistically, I used to use a custom sync setup with a WebDAV server I set up and Goodsync software. You can set it to sync in file change, and it was fast, with changes replicating in a few seconds.
As it is, the Obsidian sync takes a few minutes. And if you edit the file on another device before sync goes through, you’ll lose the changes from one device or the other.
Clearly we have had very different experiences. I have mainly markdown notes, PDFs, and screenshots and it syncs everything continuously as I work. As for "losing" the changes, I'll have to push back on that. You have full version history, so while you might have to look at an old version, you won't lose anything. There's certainly nothing unique to Obsidian with respect to conflict resolution. If version history isn't working, you'll have to talk to the developers because there's a serious bug.
This has been my biggest fear using sync. So far I haven't had any issues, but I just get a" feeling" (maybe it's the lag between syncs) that this could definitely happen.
Can you explain in a little more detail how it might actually occur? Maybe so I can prevent it from happening.
