An athlete asked me a question: 1

Why is the emphasis on long and smooth when quicker arm turnover increases the speed of my (everyone’s?) swim?

My response was to highlight three key points.

Quicker turnover increases speed IF the swimmer can hold the higher cadence, and not lose technique.
Long and smooth does not mean (or imply) slow turnover. It means long and smooth, reach and roll, which can include faster or slower turnover.
Power comes from under the water, so the pull can be faster and stronger under the water, and the recovery over top of the water slower. Often when people try to swim faster, they throw their arms over the water faster, but get less catch and power under the water, and end up with that thrashing feeling.