I used to think 5 is a good size
1. Diver / beater
2. Luxury sport
3. Dress
4. Chrono
5. GMT
To achieve this, one will need to make a lot of difficult choices (ie. APRO vs Nautilus, Calatrava vs ALS Saxonia, Speedy vs El Primero, SubC vs Planet Ocean), etc.
So my ideal suggestion will be is 5 X 2 = 10.
Two for each categories, just in case one sent in for service.
Needless to say, I am still way off from this target
