I think in general it perhaps help to be a monogamist early on so that one can get a base foundation that is tried and true and produces 100% consistent results every time.
It eliminates variables and allows for better understanding and progress in your work. Once that has been achieved, well I think it's then ok to slut around a bit sometimes.😛
I also agree that it's perhaps easier for people who tend to shoot similar things in similar situations all the time to be sticking to one film. If you are more varied in where and what you shoot, it might be better to have a couple of 'go to' combos.