timppu: I know this discussion has already gone beyond the scope that the OP intended, but just to remind that he was not complaining about lack of or delays in offline updates, but the lack of separate offline patches on many GOG games, meaning you have to redownload and reinstall the whole game with offline installers.
But as you suggested, maybe the best solution for that is using Galaxy with its autoupdate and delta-update features.
mikebert: The bottom line for me is that as a non-Galaxy user, I pay the same price for a game that a Galaxy user pays, so I would expect the same level of support that a Galaxy user receives. If this is not going to be the case, then I would like to see some transparency from GOG with a statement detailing the differences in offline installer vs. Galaxy support.
Yeah... but still, in your eyes, has something really changed for offline installers?
As far as I can tell, it never was the case that all offline installers got separate update patches. Sometimes they did, sometimes only the base installer was updated. This still seems to be the case, e.g. like I mentioned, a recent game like Cyberpunk 2077 seems to get separate offline patches.
Also, considering Galaxy introduced also e.g. cloud saves, achievements and multiplayer support, would you demand those also for offline installer users like you and me, or at least an official statement why they are missing from the offline installers?
Before Galaxy, GOG games simply didn't have any of those, e.g. if the Steam version had multiplayer support, it was generally just cut out from the GOG version (which, to me, is ok as I am normally interested only in the singleplayer part, but I recall lots of people complaining why the GOG version is missing features that the Steam version has).
I see the release of Galaxy as GOG's solution to those issues, like (the lack of) centralized multiplayer support, achievements, cloud saves, auto-update... and yes, delta-updates, so that you can receive even daily delta-updates easily, which is quite harder to achieve with offline installers.