Spam score, doesn't come down.

[Zir0]

I added disavow files for some expired domains with bad backlinks, one has 50% spam score. I believe by so the spam score would have been 10% around but when I check spam score stats same result comes even after a month around after adding the disavow files. Why? Does it take long time for the update? Also before Google was quick adding keywords when disavow files were uploaded now nothing. I read disavow tool is not used so much as Google now has become better in detecting spam links.