Also it's a matter of skill fit. To take extremes I worked with engineers experienced in mobile app game engineering, who were thinking about UI latency in obse

Also it's a matter of skill fit. To take extremes I worked with engineers experienced in mobile app game engineering, who were thinking about UI latency in obsessive detail, and engineers skilled in thinking about ML ranking problems, who had deep knowledge about the strengths and weaknesses of various ML approaches. You could've swapped their roles and it would've been a disaster, not because they're not proficient, but because it would've taken a long time to ramp up on what's important in the other's area