Jay Honeck wrote:

I don't think the maneuver you describe will harm your engine, as it
only includes cutting the power to idle. I have no statistics to back
this up, but I think it's the application of full power from idle (as
in a go-round, touch and go, or engine out emergency landing practice)
that causes the most wear and tear.

Jay, I think that is because there are no such statistics. I believe it
is pretty widely accepted that the most wear and tear on an engine is
during the first few seconds after start.

Matt