You really think so? I disagree.
She has a distinct style
- no doubt about that - but so does all
artists. You recognize her work when you hear her, just like you recognize a Metallica song when you hear it. However that doesn't mean that Metallica only records variations of the same song. They just have a consistent style.
Yuki Kajiura's music is probably more distinct than you realise. If you hear the soundtrack to that Mami vs Homura fight are you in any doubt where it's from? Do you ever mistake it for any other of her works?
My guess is "no" to both questions.
Would you ever confuse it with the rooftop fight scene in Kara no Kyoukai for instance? I sincerely doubt that.
Yuki Kajiura has the ability to create music that fits the scenes perfectly and enhances them just like a great score should. And afterwards you remember those scenes whenever you hear the score, even if you are not consciously aware of it when you watch the show.