I can confirm what Detrimiser pointed out. Even though the levels appear to be procedurally generated it seems to be more like a random value of a fixed set of possible maps. If you want to finish your run fast and efficient it is really helpful to think about the current layout in order to avoid having to clear out everything. This guide helps here a lot, from my pov. However, personally I prefer clearing out everything =).

Thanks for your comment. But i need to disagree. I played a lot of time RS and i went always through the same layout. I dont mean that the part of each map is the same, but the overall layout. The best example is Level G. I always saw the same patter, only 3 exist. Everytime the boss key is in the same room and the shops too. If you know how it is build you can say go on patter XY right,bot,left,bot and you reached your Boss room. Perhaps it is not very interessting for the normal players, but if someone plan to do a speed run it can help a lot.
And on the other hand its the question what soemone understand under "procedurally generated". For me it should mean that there exist more then 10 Layouts, which isnt really happening.

Note: Since the last big update with the new Stage i didnt played so much, i cant say if the patter were destroyed.

I know you put some time and effort in this guide. But afaik all levels are procedurally generated and therefor this guide must be incomplete and hence is pointless...