Yeah... you're not the one to say this, OldHuntsman has the exact same complain about Ren'Py SL, at first I told him that there are guides but it turns out that there aren't any that explain the whole thing properly. There are guides for bits and pieces but even those are mostly outdated. I ended up explaining the basics over skype.
We have a lot of examples in the code but those are usually either very complex or require understanding of data structure in the game, still, a lot of stuff can be found in the code.
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The trouble with highest level scripts such as SL and ATL is that they offer too many options and possibilities for very few lines of code, that is usually close to impossible to document. We had a discussion about that on lemma, where I provided examples where even the Ren'Py devs couldn't immediately give me the best advice for more complex stuff and suggested more complicated solutions instead of using higher level scrips.