There's also the factor for people who climb inside a lot that they have very inefficient movements outside.

Because the grips aren't as obvious, a lot of effort is wasted looking for placements that would be immediate indoors.

"Grips"? I guess you mean "holds" (indoors). "Placements"? That's where you place gear, not your fingers, and you don't place gear in climbing gyms. I appreciate your enthusiasm, but pretending to have knowledge of something you know nothing about is a real problem on HN (and the internet in general). Best to say nothing than make a fool of yourself – something I'm still learning.

Alternatively, they speak a different language with different terminology and are translating. I know a few climbing terms in French and they're quite different.

What would be helpful is commenting on whether their assertion is correct or not w.r.t efficiency.

It’s definitely true. The high visibility of holds in the gym makes it easy to move quickly, even your first time up it, which saves a lot of energy.

Outside, the good and bad holds are probably the same color, and may be oriented in weird ways that require some feeling around to find the best way to grip them or stand on them.

Over time, climbers outside can learn to read the rock and make very good guesses about how to reach or step for the next usable hold. But it takes time to learn, and is somewhat location-specific because of the widely varying geology of climbable rock.

> Best to say nothing than make a fool of yourself – something I'm still learning.

I love seeing people plumb the depths of irony this way.