These days quite a lot of our problems are synchronisation problems (are you pulling mutable data regularly from a remote API and storing it? thats actually a syncronisation) but despite that synchronisation and how complicated it can be doesnt seem to get discussed. You don't hear debates about different approaches, we dont seem to have a taxonomy of different techniques.

People seem to forget how hard it is. So lets say you're pushing changes from one system to another. How are you detecting changes? timestamps or a direct diff? Or checksums? Have you remembered to think about deletions? Can you even detect deletions? How do you keep track of which bits have successfully synced and which havent? If something unusual goes wrong (network goes down) halfway through a sync can you recover from that? Incremental sync inevitably drifts over time due to bugs and downtime, so are you also building a full-scale wipe-and-refresh or compare-and-reconcile to accompany the incremental sync? And dont even get me started on two-way syncs and conflict resolution and how hard that is to do without some sort of review-by-human component.