wrote:

I'm reading "Fate is the Hunter" and just read something interesting. Gann
states that they would climb to 100 feet above their cruising altitude and
then descend the 100 feet back down. He called this "flying on the step."
He claims that it bought them a few more knots of airspeed.

Has anyone heard of this? Is it normal practice? Or is it one of those
practices that have been disproven?

Personally, I've never heard of this practice.

Flying on the step certainly has meaning to seaplane pilots. You
accelerate full-throttle, yoke back and then once you're up, push
forward. The plane will then cruse on the surface of the water and you
can cut the power and remain in a high-speed taxi. I don't have the
experience to say whether the same thing can happen in air but my
intuition says that it does not because there is only one medium.