The answer will also be different at different times in your life and watch collecting/obsessing career.
I have about 16 total, but only 11 are really in my core rotation. I feel like I don't give enough attention/wear to each watch. I want to get that core number down to about 5. Five of my watches are going up for sale this year, including 3 that are in the core rotation, bringing the core down to 8. I'll see how I feel at that point.
I just recently turned that corner after inflating the collection over the last 3 years. For the 10 years before that, I was a one-watch guy. Probably because I didn't frequent this forum
