Setting '123456' as a password on any non-trivial system is not "the shortest route possible to maximize their productivity." It would be setting the password as "000000"

The guys who are really into keyboard layouts would argue vehemently that 123456 is more ergonomic as it's an "inward roll" vs 6 consecutive presses of a key that aligns to the pinky

I'm not sure, I think it's a little more ergonomical to hit six different keys compared to hitting a single key precisely six times.