Typically for me the time cost is in going down rabbitholes to attempt to improve implicit static types for getting closer to "whole program" functional type in

Typically for me the time cost is in going down rabbitholes to attempt to improve implicit static types for getting closer to "whole program" functional type inference (TypeScript repeatedly seduces me into this), and the decision inflection point is generally not for application code but for the space between application and script code, things that you might also write Perl or python scripts to accomplish...the types are especially useful in this context because they tell you a lot more about the script than your typical script, but they also introduce a bunch of overhead for a few lines of code.