Keep a route back to the files.

Synchronization keeps locations aligned; an independent recovery copy must survive the changes or access failure you are trying to protect against.

Record where each usable copy lives and what can change it; three dependent folders are not three independent protections.

Retrieve a representative file to a separate location and open it; a visible thumbnail is not a recovery check.

Deleted items, changed files and an earlier folder state are different recovery questions; act within the available history and keep an independent copy.

Track the scope, checked samples and unresolved exceptions separately; a reconciled count is not proof of file integrity.

Check source, file location and display filters before assuming deletion; preserve the current copies while investigating.

Export and verify a usable collection before cancelling or clearing the old service; an export request is not a completed handover.

Review new sources, independent copies, access and recovery evidence periodically; an archive is not finished forever after its first upload.

Keep failed or uncertain files in an exception list and preserve their source; do not restart the entire collection blindly.

Accept a defined scope only after retrieval, copy separation and intended access are checked; leave unresolved exceptions explicit.