how do you get consistent?

I feel like my biggest issue is how i learn a section really well, then when i practice another section i completely lose the section i had previously practiced. Like really lose, it's just as I simply passively learn the hard parts and then have to learn them all over again. What am I doing wrong? I feel like skill wise I could easily go for harder demons than high tier mediums/low tier hards, but this thing feels like a massive roadblock and always makes me drag for at least 500 atts everything i try to tackle