Yeah I remember seeing someone try to measure it and they saw improvements in productivity on all experience levels but they found that it helped novices the most and experts only a little.

But this is actually something I worry about. The best way to become an expert is to do things the hard way. I've talk a lot of people linux over the years and only 3 have really learned it. Every time I teach people I give them two options: the easy way, which is just how to use it and use the gui and a bit of terminal or the hard way, which hand them the arch wiki, tell them to come back after their third failed attempt to install. Those 3 people came back, but usually did more than 3 installs, but had all been successful at some point. All 3 mentioned they understood why and then we could really talk about how to use linux, make scripts (and that scripts aren't aliases...), and so on. All 3 still are terminally terminal, years later. The thing is that humans (and even machines) learn by struggling, getting things wrong, and learning from mistakes. The struggle is part of the learning process. I've found this both in myself and whenever I teach anything, that if I just feed someone the answer (or look it up and nothing more for myself) they (I) don't end up remembering, they don't end up playing, they don't end learning how to learn.