Having around 40 watches (reducing slowly), I wouldn't worry about keeping any of them charged and I just wear what I feel like wearing.
As the fool I am, I managed to buy two watches I love with just a week in between. Which poses the dilemma of having only one left arm.
So, how do you rotate them? I was thinking change every day to keep the automatic "charging" them, but that feels forced.
Also, what should I do if I leave one of them in the box for several days or a week? Rewind it daily? Leave it till next time?
Having around 40 watches (reducing slowly), I wouldn't worry about keeping any of them charged and I just wear what I feel like wearing.
It's just a matter of time...
Just wear them as you please - does no harm letting them stop. Guess you could get a watch winder if you want them 'charged' all the time.