It depends, there is 3 types of updates for KF.
- Map Whitelist Update
- Mutator Whitelist Update
- Content Update
The updates for the Whitelist (maps) are generally every 2 weeks. The Whitelist is a big list of maps that you can level your perks on. Lets say you decide to create a map, you won't be able to level your perks until you submit it for the Whitelist. Some people think that there is a blacklist, but its false. The Whitelist update doesnt require a Steam update and since there is a team to test the maps, TWI can make the updates on a regular basis.
The updates for the mutators are pretty rare. Just like for the map Whitelist, the mutators need to go through the whitelisting process before you can level your perks with a certain mutator. In this case TWI needs to look at the code of the mutator and then make a Steam update (thats why those updates are rare). If you wonder what a mutator is, you can see it as a certain gametype or as a mod for Killing-Floor.
Finally, the content updates will only happen a few times per year (or even once). Since TWI is busy with Red Orchestra 2: Heroes of Stalingrad, we dont see a lot of those updates. Most of the time, the content updates will contain a few fixes for maps/weapons/perks, new maps, new weapons or new DLCs like the custom skins.
Hope this answers your question and welcome
