NPC locations are pretty static right now, but I want to add events in the future that will shake things up. NPCs will move to a diferent place or alter their schedule outright. I agree that schedule is not a problem right now but I think it will become in the future as I add these things into the game and searching for NPCs becomes a bigger problem.
Also, I have similiar plans for the combat drops. I will be changing the way enemies spawn and give them similiar schedule to NPCs, so you can't just go to the exact same spot every week and kill the same enemy. Not to mention, I have several ideas for altering enemy population, like killing wild animals too often will make less of them spawn untill there are none. Or you can join a party trying to exterminate either kobolds or orcs, which will remove one species from certain part of the island and replace it with another. This should keep things fresh and interesting, since there will be multiple layers of patterns and triggers. It will give the illusion or things being seemingly random at first, but people playing long term will eventualy start seeing the paterns and can start taking advantage of them in future playthroughs.
Not all RNG elements will be removed though, since I also believe that having some kind of unpredictability in games is nice, but killing hundreds of enemies when you want that one specific item is not something most people enjoy I believe, especialy when you can get it on your first kill but also after a thousand.