Only if you doing something thousands of people has done before. Anything new, even very simple and you are on your own and Python is 100x slower than naive C implementation on many tasks.

Last little project I remember is writing a solver for a puzzle game my friend published. Python just doesn't work at all for such tasks.

I think you are wrong about speed of those libraries as well. In my experience naive code designed for a specific task beats highly sophisticated general code and it doesn't take a rocket scientist to get huge speed-ups over some well established fast library.