That's an interesting point, that building the smaller RPGs has helped you to make larger RPGs since you have already constructed those components. I remember in a Unity convention video on YouTube a guy was talking about prototyping and how for his company they made prototyping quicker by having a library of tools and components that they could just pop in to get things working quickly. That is something I've considered doing but I see now how easier it will be to do that if I focus on my specific genre — whatever that will turn out to be.
I can certainly say that I am guilty of not knowing when to stop my projects. That is something I can work on. For example, my garden game was never meant to be a full game it was just purely to teach me a few principles of visual design/art which I already benefited from.