In my opinion type checking in Python is a lot less necessary, which throws off the cost/benefit calculation. And the cost/benefit ratio also varies with the si

In my opinion type checking in Python is a lot less necessary, which throws off the cost/benefit calculation. And the cost/benefit ratio also varies with the size of the codebase, team and other things. Let's emphasis the "gradual" part. The more libraries are carrying type annotations, the more helpful IDEs will be and the easier it is to type-check your own code.