Obviously.
> A key element of that is making the game legible and for that you do need to spend some time on “polish” because it’s an intractable element of the whole.
What does "legible" mean? Polishing means making something production-ready. A polished feature contains (ideally) no known bugs, has been thoroughly tested, gone through several UX iterations and brought up to a release standard.
That's not necessary for playtesting and improving the game. Unless you're done with all core game mechanics, you shouldn't be polishing.