I'm still focusing my effort trying get a set of watches that covers the basics I kind of "need" as a WIS. I wouldn't even call it "my collection", as I see them more as just "my watches". I'm still there and I will start collecting afterwards (hopefully).
My strategy is similar to yours, having a permanent list, but without a yearly target. I can count many years without any while I've got three this year so far.
Let's se how I evolve through the years, still a while to my retirement π