I work with quantum physics and it is rather hard indeed, but if you read a physics textbook it still seems to leave some space for relying on intuition.
A pure math book, in some field like topology or so, seems to be much more rigourous to me, subsequent definitions, theorems and proofs al the time without further issues of interpretation, and harder to read for a human.
But I suspect applied fields like cryptography can also be involved.
On a completely different level: politics in the sense that there are no 'rules' carved in stone to be succesful, probably this is partly relying on luck.