Checking types on all function calls adds a considerable amount of extra work that I personally am not willing to pay, especially since static type checkers exist.
Me neither! I was just mentioning it as a possibility. My main use of beartype is `is_bearable` for runtime checking of specific data structures, in cases where `isinstance` isn't quite enough. I would still explore turning full checks during tests, though [1].
[1] https://github.com/beartype/pytest-beartype