King Crimson's little success?

But those songs themselves draw from widely different eras of the band, so therein the point.  Their 'signature' to the extent there is one is much wider than any of the big prog rock bands.  The main reason being that (a) the big prog rock bands usually had a stable line up for at least 4-5 albums at a stretch while no KC formation lasted beyond three at the most (and only the two best line ups lasted that long - Wetton-KC and Belew-KC) and (b) most of the big prog rock bands, with the exception of VDGG, either willingly pursued a commercial direction or were pushed into one by their labels, with only Floyd and Rush finding a middle ground where they could remain accessible without descending into silliness.  

Interestingly, the THRAK lineup only supplemented the Discipline formation rather than replacing it because Fripp was seemingly loath to let go of the stellar Belew and Levin (as also long time collaborator Bruford) and the newness came more from the long hiatus between Three of A Perfect Pair and THRAK.  Even so, THRAK-Power to Believe is one of their least impressive phases and certainly less impressive than Wetton-KC and 80s Belew-KC and did not in my estimation live up to Bruford's lofty boast that you can hear the future of music on a KC album.  Fripp, instead, was not immune to the general confusion faced by those rock musicians who refused to embrace more keyboard or electronic led trends found in both EDM (duh) and alt rock/Brit pop.  This suggests that Fripp's previous artistic success did rely on not letting a line up continue to the point where it had nothing new left to say.  

Proof positive that Bob could, in fact, stand AND play guitar!  (The lass is his sister, Patricia).

Ah, but if you apply the same riff/progression test to the other big names of prog, in the same spirit as you now propose to for KC, you will find that they repeat a lot, lot more compared to KC.  I don't have access to my keyboard for now and until the lockdown is lifted otherwise I could play motifs from different Genesis albums side by side and record clips of the same to show how similar they are.  I could do the same for Rush, Yes, ELP etc.  To say nothing of Pink Floyd or Tull who were even more repetitive.  

As opposed to all of this, you will not find the Frame by Frame riff (the fast interlocking one played by Fripp, not the Belew figure) in any of the previous KC albums.  Not only that, there is no similar riff in any rock album of reasonable repute.  There MAY be something in the deep trenches of the underground that I am not aware of, but the only riff that is somewhat like the Frame by Frame is the one on Talking Heads' I Zimbra.  Which featured Fripp on guitar so I guess he had something (or maybe a lot) to do with that riff?

I am not saying this because I am a KC fan.  Because I am a fan of all those other prog rock bands I mentioned above as well.  But I haven't heard where they radically reinvented themselves in the way KC did on Discipline.  Likewise, the change from ITCOTCK to Larks-Red is drastic.  To take only Schizoid Man and compare is the wrong way to go about it.  ITCOTCK also had lush symphonic prog by way of I Talk To The Wind, Epitaph and In The Court of the Crimson King.  Fripp completely moved away from it on these albums with only Starless having nods to symphonic prog.  

Again, ITCOTCK, in totality, has nothing like the slow guitar-bass progression of Starless or even the dramatic guitar-saxophone breakdown that follows.  Even the middle section of Schizoid Man is very structure and almost tame compared to the instrumental section of Starless.  From the other bands, the only one that at least undertook a comparable journey as ITCOCK to Red is Yes from TFTO to Relayer.  

I would go so far as to say I don't even think Genesis had the capability to reinvent themselves so dramatically (which is probably why three man Genesis chose to go the pop way given they were always capable of writing catchy pop-rock songs).  Maybe Collins by himself could adjust to any kind of music but Banks and Rutherford were relatively limited while eminently suitable for the music they generally chose to play.  In Rush, similarly, the weak link was Lifeson while Geddy and Peart seemed to be capable of getting to wherever they wanted to. This was another reason Fripp kept shaking up the line up (and then got stuck with the Belew-Levin-Bruford formation); he only wanted flexible and adaptable musicians in his line up which was fair enough seeing as he himself was prepared to unlearn and re-learn so much and keep moving. 

Rush rant:

****I think that's the second time I've seen Lifeson mentioned as the weak link in Rush on this forum. If your definition of "weak link" is least technically skilled player, I guess he might qualify, at least in the shadows on Peart and Geddy (in most other bands he'd be a leading talent). If it has more to do with versatility and variety, I reckon he's in the upper echelon. There's little resemblance between his playing on Working Man and his playing on Red Sector A. Even the jump between his solos on La Villa Strangiato vs. his solo on Kid Gloves is astounding. Alex's playing evolved to fit what the music called for. If he'd been unable to adapt, then the band never would've evolved or they would've fired him. And if it comes down to writing, Lifeson is responsible for coming up with probably half of all the music in Rush's discography, maybe more. Geddy wrote too, especially in the synth years, but for a lot of the more guitar oriented stuff I have a feeling he mostly followed Alex's lead and wrote a melody to go on top. Take Lifeson out of Rush and it isn't Rush at all, it's just one of the best rhythm sections in rock and roll.*****

But back to the topic. Even if KC is one of the least repetitive bands out there, which in many senses they probably are, I still hear commonalities in the music spanning their whole run of 70s releases. The slinking jazzy riffs on Pictures Of A City seem to me an obvious influence on the moody bass driven improv of the Wetton lineup, and certainly on the slow build up jam in Starless. That's not to claim it's the only relevant or important influence, just one of them. I think I hear similar melodic instincts at play between Epitaph and Fallen Angel for another example. If nothing else, Fripp's menacing guitar tones may have evolved from album to album in the 70s, but it's a very directional evolution, as though with every album he gets a little closer to the sound of Red and a little further from the sound of 21CSM. Sailor's Tale is certainly a precursor to his work on the next few albums. I'm not arguing that KC didn't drastically change between most every album (the first two being an exception), but that for all the drastic changes to their sound and style, certain components of the ever elusive KC sound were always present in some form or another. I really think to find any band that shifts so drastically between albums that their earlier work has nothing remotely in common with their later work is a practically impossible task. Musicians are always going to sound at least a little bit like themselves.

I give Lifeson more credit than that for the 80s stuff. He generally liked most of the material they played, he just got tired of it after almost a whole decade (and did have his quibbles the couple times a synth solo replaced his guitar solo). But I can see the argument that he isn't the greatest among the likes of Howe or Fripp or some of the other prog rock juggernauts. I disagree in my personal taste, but I can see it.

But yeah totally agree with what you're saying about KC here. And that Radiohead anecdote is a great point. There was a time when I didn't really like Iron Maiden, despite loving a lot of other classic metal, and one of my main reasons was that they just sounded to samey from song to song. I dug in deeper, heard a song or two that surprised me, and eventually fell in love. Now I still think they're kind of the AC/DC of metal (it's either them or Slayer), but I hear through all that sameness and find the key differences between songs that makes them each unique. So I definitely think that people who don't like a particular band (or at least don't "get" them) are prone to thinking all their music sounds the same. I wonder if that holds water with critics of Queen, lol.

Good question, because I consider both bands to have peaked when Bill Bruford was involved! I'm a Yes fan boi to the end, but LTIA just might have a bit more complexity than anything Yes every put out with Bruford.