kilobug: From my own experience with "big new games" on GOG like WL2, the patch will be available on GOG 1-2 days after it's released by Obsidian, which is a perfectly reasonable delay.
cudds: No, it really isn't . GoG is getting a fully working build of the patch from the developer studios. The only thing they need to do is rebuild the release with their own installer, which should take about 10-15 min including configuration of the installer properties.
I never understood the crazy delays with GoG patching, unless they manually gametest the patches for several hours there is no reason for these to be this long. And testing the patches should be the responsibility of the game developers, not GoG.
AS Gog change the patches (including the numeration) to own needs, Gog need to be sure don't screw it. Then again, the Gog bet to how handle old game was a big mistake as now they don't focus only on the old ones, that is why Gog Galaxy is being developed.