Why do the big fixes still defeat me?

You can design most remediations now. Say that plainly, without false modesty. The skill is real. But the large ones still beat you, and you know it, and it bothers you more than the small failures ever did. Here is what is actually happening. With the small problems, you see the whole shape at once and move. With the large ones, you try to do the same thing — hold the entire design in your mind before you act — and the scale will not allow it. No one's mind holds a large remediation whole. That is not a flaw in you. It is a fact about size. You are not working alone. You have a team. Use it as more than an audience for a finished plan. Bring them the unfinished one. Let them carry pieces you cannot carry by yourself. The large problem does not need a bigger brain. It needs to be cut down and shared before it is solved, not after.