No storage limit... but how much can Nextcloud actually handle syncing?

I understand that Nextcloud, when connected to local storage or a self-hosted server in a LAN network (TrueNAS in my case), has no storage limit besides the limit of the server’s storage capacity.

What I want to know now is… how much can Nextcloud actually handle?
I ask this because, upon trying to resume sync after a large backup (600+ GB), the client seems to want to check every single file to see if anything has changed. Similar to how long it took to upload in the first place, I predict this check will take at least 24 hours, and I’d rather not have to do this all the time.

Will the client do this every time I sync, or is it smart enough to know not to check everything after it’s completed a full sync once?

It’s difficult to give precise numbers. It often depends on the server as well and how fast it reacts (depending a lot on caching and other optimizations). For the desktop client, there were contributions here that report long checks on the file system for large sync folders.

For many clients, I tried to limit the synced data on the required data on a single device, e.g. >60k files and 35 GB, there is no problem. A different client has lower hundreds of GB, that is ok as well. The clients are connected on a regular basis, there are not many changes between connections.

If you find some hints in your logs, you might be able to create a bug report, or check if there are known problems already.