So what, I’m only expected to bring 40% of my abilities to my next job? That makes mathematical sense, but it’s impossible in practice. It would be like trying to use 40% of your arms.
If an honest engineer sees a problem which is exactly the same as one she solved at a previous company, and it is still the best solution, she will solve it in the same way. This has nothing to do with company secrets, it’s basic tradecraft. But it’s covered in many of these agreements. They’ve got to go, plain and simple.