I understand what you're saying, that to beginners there are a lot of "unknown unknowns", but not everything should fall into that category. Even with a real-life teacher or mentor I'd give the same advice: go to them with a problem you're having or something you're trying to work on, rather than asking for general tips on how to get better.

We might have different fields of study in mind. In everything I've studied, even a beginner should be able to compare their work to the work of others and identify things that they need to work on. Do you have an example of a field of study where a beginner could look at their own work and not be able to identify anything that needs improving?

I was thinking about my experiences drawing and painting. If you do something like impressionistic it can be hard to judge, did I do to much detail, not enough detail. With pen drawing it took me awhile to realize how much more depth i needed to add by using darker values. It did take me a while to have that click. I suspect it would have been obvious if I took a drawing I did and one I considered well done to compare and asked someone experienced to point out the differences.

But also personally when writing it helps to get feedback to a vague question like what do you think. The writing I've done is non fiction, technical blog like stuff. I think the vague question of "what do you think", "how can i make it better" works there because it stands alone. Even when presenting a picture I can almost kind of prime you're reaction with a blurb about it.

> go to them with a problem you're having or something you're trying to work on, rather than asking for general tips on how to get better.

I agree with that, you does help to have a goal when asking for help to make it effective