[mr_mitm]

When you have tenure, you can work on whatever you want for as long as you want. Nobody works on an idea for five years without publishing anything, though. Progress is made step by step.

Take Albert Einstein as an example, who arguably made one of the largest leap in physics with his theory of general relativity. He never stopped publishing during that time.

[p1esk]

When you have tenure, you can work on whatever you want for as long as you want

Not quite. When you are a professor, you essentially become a manager for a group of researchers. You don't really do research yourself. Therefore, your main obligation becomes finding money to pay these researchers. So in reality you can only support the research someone is willing to pay for (via grants, scholarships, etc).