I guess one of @smckk's main points is that when one looks up tutorials and guides they tend to be introductory. Meaning they don't go to intricacies of critical refactors to introduce major new functionality etc.. i.e. I think @smckk wants to see how people approach the thinking about changes beyond the "initial build".
@smckk the closet thing I can think of that may help you is to visit large company's engineering blogs that sometimes do small to large writeups on big changes in their architecture, code organization style, etc. It's not as detailed as seeing the actual changes line for line but it can help guide your thinking of taking a piece of non-trivial code to another level of non-trivial code if that makes any sense.
That makes sense. But to me those are largely functions of experience with a toolset/platform that are expanded with product iterations and not something to dwell on.
@smckk the closet thing I can think of that may help you is to visit large company's engineering blogs that sometimes do small to large writeups on big changes in their architecture, code organization style, etc. It's not as detailed as seeing the actual changes line for line but it can help guide your thinking of taking a piece of non-trivial code to another level of non-trivial code if that makes any sense.