I'm sorry but I think the lady at the class is wrong. I really think they form a bond whether they have time apart or not. And, if they WANT to be together, I believe letting them be together far outweighs any future problems. They will be happy "now."
Mine are really close, but they do spend time apart when both my husband and I are out of the home...simply because my older dog is 55 lbs. He would never hurt her on purpose but they do love playing and roughing around...it wouldn't take much for him to accidentally hurt her. When one of us is at home, though, the furkids are always together. I can't keep them apart