I have an idea of roughly what I'd like to own in the long term, but if I like something and can get a good deal, I'll get it.
That said, I do also cull my collection pretty aggressively. I tend to only have two watches at any given time, so it often operates as a one-in, one-out rule. In the long run I'll probably cap my collection at three (dress/daily, dive, and maybe a GMT) or four (I'm likely to inherit a watch that I'll never sell).
Those pie pan constellations are really special. I feel like the GS is a bit generic in comparison.