This is all pretty interesting and a lot to think about
from various aspects.

Some of what's already been said deals with what's
right for those involved and in my mind I'd say that's
a key element in pretty much all things.

Although I've never been much solely about the numbers,
if it was a nice blend and satisfied all involved I would
again and have taken that position in the past.

Sometimes you find that you establish a connection on
one level with someone while you do so in a different way
with another.

Tojo mentioned this earlier about being able to meet specific
needs on one level and someone else providing the other.

Overall I think it's practical as well as plausible to have
more than one master or mistress providing it meets their
needs and establishes a nice balance for everyone concerned.

All in all a matter of personal choice so I don't feel there's
either a right or wrong answer for this question. It's all
pretty much in the eye of the beholder on this one.