really unsure how anyone could say the 'hard prog fusion' trilogy (Red / Larks / Starless) sounds that similar to everything prior. there is much, much more continuity between Court, Lizard, Poseidon, and Islands, which was then severed with the 'Mahavishnu Orchestra meets Pink Floyd' sort of thing happening on R/L/S.
thus, the most accurate (imo!) KC breakdown would be four 'eras' regardless of breakups and lineup changes:
1969-71: In the Court of the Crimson King / In the Wake of Poseidon / Lizard / Islands
(fusion-developing freakouts blended with pastoral quiet pieces)
1973-74: Larks' Tongues in Aspic / Red / Starless and Bible Black
(balls-to-the-wall fusion, more improv-based, some Frippertronics, developing 'commercial' side influenced by stuff like "Have a Cigar")
1981-84: Discipline / Beat / Three of a Perfect Pair
(that '80s chorus guitar sound, mostly contrapuntal guitar writing, Belew vocals, balance between spacier instrumental material and a new 'commercial' side driven primarily by Belew's wacky blues influence)
1995-now: Thrak / The ConstruKction of Light / The Power to Believe
(incorporating electronic sounds like drumpads and Fripp MIDI-guitar controlled synths, retained some of the Belew blues influence, spacier but bombastic and explosive)
obviously each of those eras has a lot of leeway (Thrak was written and recorded with the double trio, for instance, whereas ConstruKction and Believe were quartet records) but there is a definite amount of consistency on an objective level within those eras.