I think it's an excellent idea.
Children go through much the same thing every day, from the day they're born, if their parents both work. Home, then to daycare or school for several hours, then back home again. Home all weekend. It doesn't seem to negatively affect them, and leads to good social skills.
When I get a new dog she's going to be "co-owned" in a manner. She'll be spending many of her days at my friend's office and the rest of the time will be spent here with me.
I think that it will make for a very happy and well-adjusted dog. The different people and sounds, different routines, etc. will hopefully help the dog to be very mellow, easy-going, and trusting.
:)