You may have to manually step through the conflicts menu to resolve them, choosing which device's version to keep. But typically that won't happen unless both device's versions of a file change at the same time.

I have been using syncthing for at least 3 years now. Sync’ing a 7gb directory across 6 devices. I rarely get conflicts, when it happens i just click on the conflicts link via the browser and check which files are conflicting and try to resolve it. Sometimes i have to call a REST action to reset the local db:

  curl -X POST -H "X-API-Key: xxx" "http://localhost:8384/rest/system/reset?folder=YYYY"

This is my last resort cause sometimes syncthing gets confused.

Also good to note my setup has 1 introducer which is my NAS (synology) that is 24/7 online which always has the latest changes. Other devices are mostly mobile or turned on at irregular times. For devices without syncthing support like iOS, i rely on exposing the directory on the NAS via webdav. This way i can still access my data on the go.

And my synology creates regular backups/snapshots of my synced directory. So that i can always recover files. Even outside of syncthing.