I've noticed that on Kill la Kill that Goku Uniforms can only be made from 10%, 20%, and 30% life fibers. But later on, it is revealed that a Kamui is made of 100% life fibers. That seems like a major gap to me. How come a uniform can't be made of 40%-90% life fibers?
No characters we see can wear 40%-90% life fiber uniforms who cannot also wear 100% life fiber uniforms.
The only people who can wear 100% life fibers are not 100% humans (they have life fibers experimentally infused into their bodies). No pure humans have been shown to be able to wear more than a 3 star uniform.
Well, a normal person can not handle above 40% life fiber, even student council had pre-training to wear them and they are also selected few to wear 3 star regalia (above 30% to 40% life fiber) from the entire school.
We can see what happened to people who wear 100% life fiber: it gives a huge amount of strain to their bodies. Remember when wearing Junketsu or Senketsu, Kiryuin Satsuki had to maintain great will power, discipline and great amount of physical strength. Even so, Kiryuin Satsuki can not gain the full benefit of Junketsu because she is just a human.
So in short, generally, normal humans can not wear 100% life fiber, but if you keep on building up your physical and mental strength around long period of time, you might have a chance to wear one. Still, you won't get to have full power set or full benefits of it due to inhuman strain on your body.