HF can reflect off the antarctic, which can be heard as a kind of warbling effect when communicating over the pole between US and Australia for example.
This is not how artists work at all. I don't think any school of art has done that, other than for very rough composition (where objects go in space). Most schools of art from deep history all the way to today train with copying/sketching from life (training the eye to go where you want it), while also teaching general truths about light, color, proportion and anatomy.
People who draw out of thin air usually have these trained references in mind, so when they draw a pose they're not so much simply copying from their imagination, but from facts and past experience, about knowing about anatomy, light, and proportion. You draw as you go and see what's on the page, and you can build out a world that didn't exist, but not so much from mind's eye, but somewhere in-between the page and prior experience.
None of the above training or sketching would be needed by someone with a photographic memory or an imagination that can hold that level of mass detail (they'd only need to know practical techniques their medium depends on). There have been people like that such as Austin Osman Spare, but in the main the vast development in art has to do with learning about anatomy, proportion, light, color, and technique as taught by all the great masters.
Cartoons are a good example how a style comes not so much from the imagination, but how one very naively and simply draws characters and then builds off that natural style into something refined. This comes from playing on the page, not imagining what one wants. If you copy other people's cartoons you can also learn different lessons, and that has to do with training the eye and technique.
If this were true all siblings would have similar anxiety issues, but I'm willing to bet this is not really the case. IMHO most mental illness is genetic, or at least the predisposition is, which can than be triggered by upbringing, but it can also be triggered at every other point in your life so... I mean... And Kids will spend a lot of that time in school; parents have to be pretty darn overbearing to get to the level of school-like schedule and behavior control, so again, all very dubious this is all down to parenting.