I don't know, honestly, I don't think I could own 6. I love love love dogs and if I had some sort of a big facility to keep them all I would. But as pets living in my home 24/7, I think I'd go crazy. I feel like I wouldn't be able to devote enough time to each of them and think that w/ owning multiple dogs, you really truly need to define yourself as their leader or it's going to be
chaos. I also believe in dogs having socialization with other dogs besides their own "pack members" and it wouldn't physically be possible to bring 6 dogs with me to the dog park or for a walk (unless you do it separately).
So, me personally, I would opt not to add another one for those reasons as well as financial. I enjoy so much bringing Jackson to my family and friends homes, or for play-dates with other people and their dogs, or to dog parks, and think he really enjoys it too. It wouldn't be the same with 6 or 7 dogs. I know over at my dad's house, they have two small dogs and when I bring Jackson over, it makes three, and it turns into chaos at times. Their dogs aren't that well trained so their energy totally reflects on Jackson and he turns into a completely different dog! But if I did have the space, money and time, I would love to have a dog "farm!" LOL. Like Cesar Millan's pack

His center is awesome. But as a general person living in a home, no, I wouldn't take on that many dogs as much as I love them. I spend enough money on one! :P I think fostering is a great and wonderful idea because you're helping out a dog in need. Most people are more wiling to adopt a dog who has been house trained and socialized a bit and taught how to live in a home.

Personally speaking, I think 3 is the highest number I could own at a time.