Writing code that type-checks whatever input is coming into your functions may only take time, but what really are woes that you will have fewer of the stronger the type system, is that you have to
design the code that runs when those checks fail.
That designing requires thinking, and thinking takes your attention away from whatever your goals are, whether you are used to it or not.
Strong type systems come with their own things that require extra thinking, but I think it is less than what is required to write robust dynamically typed code.
Many projects don't need truly robust code. Then, the dynamic language may still win.