How does "turn off Water Lock and eject water" work?

It uses the speaker to eject the water, this ejects most of the water that has entered into the speaker (not actually entered into the watch)

From:

How to use Water Lock and eject water from your Apple Watch - Apple Support

"A series of tones plays to clear any water that remains in the speaker, and then you can use your display as usual."

I don't know, as far as I know there is no setting for this.

It might be that she has either a different model of watch, or a different software update. And there is some difference there. if not I don't know

Derfyef wrote:

Why: on my watch I only need to spin the crown a few times. on my wife's watch it takes many times?

Differences in how fast and how far the user is spinning the knob? Hardware or watchOS differences? Donno.

Spin it, release the water lock, move on.

If you really want to know, you have the hardware, so run some experiments, collect some data on any RPM and spin time differences used, plot your results, and discuss any differences found with Apple. (Though they’ll probably be respectfully amused, and will tell you to spin the crown until it unlocks and move on.)

Or if you want to know how to shut off the water lock, spin the digital crown knob—quickly—a few dozen times…