How often does Garmin do an open street map update?

I have a feeling it might be every 6 months. I think that's the release interval for mapping on the devices. 

It would, ideally, be a lot quicker. I also use komoot and that updates every two weeks. 

A 6 months interval would be awesome! Unfortunately it's more like a 6 years interval (or even worse). The garmin connect osm map (at least in my area) has not been updated within the past 6 years. I can tell because I started contributing to osm somewhere in 2019, and my map edits are still not visible on the osm map on Garmin Connect. 

that is really disappointing. Why would they not update more often a free and common resource?

I was considering contributing for the sake of better garmin trails in my area. But that does not seem to make sense.

I'll contribute just for OSM sake then..

Yes I know, super disappointing. OSM is available for free, and even hobby projects manage to update their maps regularly, but not a multi million dollar company like Garmin...  It seems like the Garmin Connect team simply does not care about the OSM map, this would also explain why they never made it available on the mobile app. 

But still your OSM contributions might be valuable for your Garmin user experience. Topoactive maps (the free maps that come with devices with maps) are based on OSM, and these are updated once or twice a year usually. Also the topoactive maps in the Garmin explore app might be updated more frequently (i did not monitor map updates there yet, but at least the app it is regularly searching for map updates).

We can of course only speculate about the reasons behind Garmin's map update strategy, but from my own experience OpenStreetMap is not the easiest map source to work with.

I have used OSM-based data as a map source for a routing programming exercise on my data structures and algorithms course. Since data in OSM is provided by many different individuals with different skill levels, it's typical that (especially with forest paths) path/road segments do not end in exactly the same coordinates (even though it looks like they do), paths cross each other without there being a common point in the crossing, etc. All this requires extra work to get routing working even remotely decently, even if the map looks ok. And Garmin maps (to my knowledge) are not based only on OSM, so that creates additional hurdles in producing the final routable map.

Another potential reason is that most OSM-based hobbyist maps probably get at most tens of thousands of downloads. Garmin maps are >10 gigabytes, and there are millions of people downloading them, so the amount of traffic is much larger. I'm just guessing that that might be another reason to publish a map update only 1-2 times a year.

But of course I'd be happier if Garmin updated its map source more often.

1-2 map updates a year would be perfectly fine with me. What is not acceptable is not updating the map in 6 years, like the OSM map in Garmin Connect.  

What I forgot to mention before, and what might be interesting for dosch: The routing layer seems to be updated more frequently. So when you plan a route in Garmin Connect, even if the trail is not visible on the map, the route planner is still using it. I have no idea how often the routing layer is updated, but it is more often than the visible layer. 

That's interesting! When I read this thread I checked the area that I remember was one of the first I edited in 2019 and the edits are not there. This is in Austria. 

So it seems some areas receive updates, others don't.