I've seen this happen but without that "without reading" part. I've had a coworker, who about a 1-2 weeks after starting working in erlang (without prior exposu

I've seen this happen but without that "without reading" part. I've had a coworker, who about a 1-2 weeks after starting working in erlang (without prior exposure) on our big codebase was already able to contribute some fixes and soon new functionality and he was not even considered as senior dev when hired. Most of my coworkers are experienced and also able to work on new codebase pretty soon if required. They are not that rare.