It used to be three months of developments and that's how often the updates were released until 0.6 which took more than 3 months, sucks it has gotten longer
Not really.
The first release was posted in September, 2021 (you can get this by looking at the initial post date of the OP - unless the page somehow gets nuked and recreated, that corresponds to the initial posting of the VN here, at least within a period of a few days); update 6 was posted yesterday - that's 25 months elapsed, and five updates since initial post, which gives an average of 5 months between updates.
I got here just after update 0.3, it think (second update) and the next two updates, 0.4 and 0.5, were pretty close to that 5 month average, give or take a week. My download for 0.5 is dated January 24, 2023, dropping here within a day of top-tier release, so this one took about 6 months to drop, though the work on it was probably closer to 5 months since Cari is in the habit of taking a breather after each update. I would expect each subsequent update to start hitting around that six month mark, give or take a week, since this is a mature VN and it naturally has more complexity, at least if the size of the update remains about the same. If Cari decides to drop a scene to speed release, then we might get things faster, but we would have less play time. For me, each release is usually over 3 hours but less than 5, depending upon how much I explore alternate paths, how many screenshots I take, and how many times I replay a series of slides because I found them too good to not redo immediately.
If there was ever a 3 month update, it may have been 0.2, but I wasn't around for that and I seriously doubt it was that fast. Caribdis is known for quality and quality takes a minute or two.