There isn't a set interval for data updates. However, the process is mostly automated and new data can be fetched fairly quickly. So, updates will occur regularly, but you'll likely see the most movement around the monthly FEC Filing Days.
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Good question! It's because they aren't maps at all! They're cartograms. Specifically, they are Congressional District Hexmaps by Daniel Donner for Daily Kos Elections. Maps are really good at telling us some things, like where things are or what shape a given geography is. But when we're talking about things like Congressional districts or groups of people, maps tend to give us the wrong impression. Just because something is bigger doesn't make it more important. Since Congressional districts all contain (roughly) the same number of people, it's helpful when our visualizations are the same size. A single district in Montana might cover a large geographic area, but it still represents the same number of people as a geographically tiny district in Chicago. The Hexmap cartogram is an excellent way to visualize Congressional districts because it maintains population proportion while roughly correlating to actual geographic locations.