In my first art, kata were introduced at the rate of one every two years after 3-5 years of training basics, conditioning and hard contact sparring. I know three and a half kata from my old system (after 8 years of training in it), but wouldn't trade them for "knowing" a dozen or more kata taught for typical belt tests.
At this stage, I honestly have no idea how someone could truly benefit from kata without having a solid combative base, or how someone could claim to really know a kata after less than a year. Older katas are really collections of advanced tricks and repeated movements that can make you look at fundamentals in new ways. The movements are often deliberately simplified to ease teaching and to keep from limiting your ability to interpret them. Most movements are not really "finished," except for one or two base applications. If you don't have a basic fighting system in place, you won't be able to make use of them. If you don't know how to modify a reverse punch in the dojo to an effective cross or use the chamber to grab and anchor, then similar principles in the kata won't appear.
That said, I'd put sets like the Pinans in a whole different category. They string together kihon and are not really katas in the same fashion as Naihanchi.
At this stage, I honestly have no idea how someone could truly benefit from kata without having a solid combative base, or how someone could claim to really know a kata after less than a year. Older katas are really collections of advanced tricks and repeated movements that can make you look at fundamentals in new ways. The movements are often deliberately simplified to ease teaching and to keep from limiting your ability to interpret them. Most movements are not really "finished," except for one or two base applications. If you don't have a basic fighting system in place, you won't be able to make use of them. If you don't know how to modify a reverse punch in the dojo to an effective cross or use the chamber to grab and anchor, then similar principles in the kata won't appear.
That said, I'd put sets like the Pinans in a whole different category. They string together kihon and are not really katas in the same fashion as Naihanchi.