Crate training helps in so many ways. I have two puppies, brother and sister and without crate training, we would not be as far as we are.
First, of course for the house training. Crates make this a lot easier for us and the dogs.
Second, they need their own "identity". It took me a few weeks to get crates for them and they were like two dogs using one mind. As soon as I got the crates, overnight it was a staggering difference in their attitudes and how well they listened to me. (I also walk them separately and train separately.)
Third, it's their place. (Each one has their own crate.) They are the only ones allowed in their crates, that's their den.
When I first put them in and had them separated, mein Gott! The screaming! OY! It went on and on and on and on....it wasn't just whining, it was full on tantrum. Sakari flung herself against the sides, scraped at the tray, screamed for an hour straight. I wondered if my neighbors were going to a) kill me or b) call the cops on me because you would think this dog was getting a leg severed the way she was screaming.
I ignored her and she eventually got the picture...screaming and throwing a fit isn't going to get you a thing. Wow, this is waste of energy.
Now I can put them in their crates, go to work and come home around lunchtime to let them out, back in the crates, back to work, come home, let them out to conduct their business transactions at the Green Lawn Bank, give them some play time together and then....
Fourth, I feed them in their crates. This way they don't gulp, they chew. They don't rush, they take their time. There is no food aggression like there was before the crates. (Plus it's easier to keep clean than mopping the kitchen floor every night.)
When they are done, I take one out, disinfect the tray, take him/her out on a walk, play a bit of chase and tag, tire him/her out and come back.
I then put that dog back in to the crate and take the other one out. Lather, rinse, repeat.
When they have both been fed and had their walk/play time/training time, they are allowed to be in the house out of the crate but even then one of them is next to me at all times and the other is in a doggie bed a little bit away. They are still in the same room but not together and therefore, controlled.
They will also sleep in their crates at night time. It is a lot of crate time but it's for training many different things and it won't be forever. They'll always have them but eventually they won't have that much crate time unless they want it.
As it stands, sometimes the boy will go in the crate on his own if it's his turn not to be the one next to me. He chooses to go in there even though he's been in there most of the day. I guess it's not so bad for him. The girl, she still doesn't really like it but she doesn't scream and throw a fit anymore. She accepts it...but she'd rather be out.
Edit, I forgot to add the Fifth: Because we are still learning how to act and behave around the cats. At this point, I am not going to leave them with my cats, unsupervised. They aren't mean, they are rambunctious and play rough. Sure, the cats swipe their noses but they still need to learn and the crate helps keep the cats protected and gives them a bit of peace throughout the day.