The Dom side of the coin has been mine for the last 10 years or so. The relationship I was in varied from only the bedroom at one extreme (at first), and right down to every detail of what my slave wore to work (or didn't wear on certain days) at the other.
Obviously, it requires a lot of trust from both sides. For most, everyday things like work, family, kids, grocery shopping and keeping the house clean set limits even when people set out to play their roles 24/7.
On the play side (and excitement side), it takes a lot of work and discussion to find out your partners desires and make them happen. I think that's why some subs/slaves like the control - they know when it's well done their needs are being paid attention to as much as the Doms/Dommes, and recognize it takes a lot of effort. Since the pleasure of the slave comes at a price (pleasing Master or Mistress), there is a kind of balance.
Personally, I've always preferred monogamy in a slave relationship, but some Masters/Mistresses feel it's important to show the slave they can be shared like a pair of socks. I guess I'm too greedy to do that - HEH!
Osiris