Sometimes I do code that fast. When you’re messing around just trying to find out if something is possible you want to write as much code in as short a time as possible, and Python shines for that. Every second wasted typing is a second that could have been spent moving forward.
Of course the problem is that the prototypes are terrible to maintain and eventually need unit tests and typing. But you don’t want to waste time adding those things if you’re not even sure your idea will work. I use strongly typed languages in production and couldn’t imagine using Python for that.
If typing speed is your main limitation, it means either you can improve your productivity dramatically by improving your typing skills, or your language is limiting you so much that you don't have good abstractions to enable you to think at a higher level.
I don't see how typing F# is slower, longer or less convenient than typing Python (spoiler alert, it's not). And you also get things like actual lambdas, pattern matching, currying, real parallelism and more and more.
It's only that people believe there is no need to learn anything beyond Python because it's "easy", which it's not, once you go beyond several hundred lines of code. But the myth somehow continues to persist.
This logic transpiles(TM) to this in my brain:
a) I am messing around and need to write 10 lines of code. Can I write it fast and without thinking? Sure and not needing to type int/float/whatever will save me couple of seconds. If I iterate and rewrite that short piece 10 times then I just saved 20 seconds. Chirp chirp ... . Do I need special language for just that? Lemme guess ...
b) I am messing around and need to write few hundred or thousands lines of code. Can I write it fast? Maybe but it is likely that good chunk of time will be spent thinking. I doubt that at this point not declaring type will save anything worth noticing.
But that of course is my opinion
Typing speed is only one constraint that type systems enforce. They also make it much slower to change input or output data from functions. I tend to use dynamic languages for projects between 100-500 loc and usually I’m not really sure what the final design will look like so need to try a lot of different ideas as fast as possible.
Of course the problem is that the prototypes are terrible to maintain and eventually need unit tests and typing. But you don’t want to waste time adding those things if you’re not even sure your idea will work. I use strongly typed languages in production and couldn’t imagine using Python for that.