Stumbled on this in the latest patch notes for Grim Dawn:
https://forums.crateentertainment.com/t/grim-dawn-version-v1-2-1-6/146187

- Our latest update is now live on Steam!

Our resident GOG build pusher is on vacation, so unfortunately GOG will have to wait until July 9th for their patch.

So at least Crate has a completely separate process flow for rolling out GOG updates. If most studios operate like this, the amount of blame for always getting updates later than on other platforms might be lower on GOG's side than expected. That it is not just a matter of Steam for example, processing the update faster, or GOG installers taking too long, but a matter of a lack of (or late) action on the dev/publisher side.

It really shouldn't be that much of a difference.

At least, not with a competent build/version control system in place.

When I work on my software I need to send its builds to distinct places, so a delay is unavoidable for anything but the first target. Said delay is usually less than one second, and I don’t think it ever went over five seconds between the first target and the last one.

For something as big as a video game, I could understand a delay up to a couple hours.

Even that way, taking care of Steam first and of other store afterwards is a choice by the developer or publisher. A common DRM-free build for stores providing that could be sent first, and the DRMed builds could be built/sent only after that. It is not done that way because the studio wants Steam to be updated first, not because they need to.

It's fair enough for someone to take vacation.

As far as blame goes: company workflows can be immensely inefficient or immensely efficient so you cannot judge one company's productivity by another company's workflow.

Two weeks is slow but not a horrific delay to get a patch so (sorry but) seems like a non-news-worthy update tbh.

edit: I get what vv221 is saying and I agree in principle but if the person in charge is already on vacation when the patch drops then I understand the delay too

There were a couple patches for Grim Dawn where GOG's was live first. I remember them fondly.