Jak (who will be 2 years old in June) and Gypsy (who will be 5 years old at the end of this month) probably get to play together on average 2-3 times a week, and sometimes not that often. Jak stays outside in his kennel most of the time, and Gypsy stays inside most of the time. I feed all of mine separate as well. Jak eats in his kennel, Gypsy eats downstairs, and Jessie eats in her crate or in the kitchen if she's loose in the house when I feed her.
I didn't get Jak until he was 5 months old, and he was separated from his littermates at 7 or 8 weeks old. The breeder doesn't let puppies play together because of them becoming 'too doggy,' and also because he doesn't want them dominating each other. After I got Jak, he didn't get to play with Gypsy until he was probably 7 months old, and then it was only for short sessions, so that I knew they'd be able to get along.
Jessie (8 months) doesn't get to play with Jak at all, because he's too rough and tries to dominate her (and doesn't back down when she submits). I cannot have all three out together at all because Jak gets possessive of Gypsy and won't let Jessie near her. I had to whoop some Jak butt a couple of times because of that, and now I don't even try to have him out if Jessie's out. I'm waiting until she's grown and matured a bit before I try letting her and Jak be loose together (sans Gypsy at first). I'm thinking his behavior will change once he figures out that Jessie is intact. :lol: Right now, they interact through the chain link of Jak's kennel outside, and through the crate door inside (if I bring Jak in the house). She only gets to play with Gypsy maybe once a week, maybe only once or twice a month. Again, I didn't get her until she was 5 months old, and she came from the same place Jak did, so she didn't have any direct doggy interaction from 7 weeks till I got her.
Honestly, the only reason I let them play together is to burn off some energy when I can't walk them or do any training with them.
Jessie does NOT tolerate other dogs coming into our yard or trying to bother us on walks, but has never shown an ounce of aggression towards Gypsy or Jak.
Jak acts like he *wants* to play with other dogs if they're coming towards him or whatever, but he doesn't really know how. He just jumps on them and if they submit or try to get away, he goes into 'predator going after prey' mode and won't leave them alone, and gets rougher and rougher with them. I don't know what he'd do if he jumped on a dominant or aggressive dog. Never happened. I can call both of them away from another dog, though, and none of my dogs play or interact with strange dogs.