A dog never forces another dog on it's back unless they intend to kill that dog. The submissive dog when it knows it's done wrong will place itself on it's back as a sign to the dominant dog. This behavior was observed in wolves and completely misinterpretted which led to the "alpha roll". Forcing a dog on it's back is a very bad practice. It can make both fearful dogs and dominant dogs much worse and cause them to act out or bite out of defensiveness. It is also never necessary. Like I said one dog only forces the other on it's back when it intends to kill it. If you show dominant behavior and threaten your dog it should just fall over. I've put my akita on the ground before but I didn't have to flip her over and hold her there. I grabbed the scruff of her neck and pushed in to her space. She fell right over and laid there until I moved back even after I'd let go of her neck.
The other problem with using such strong discipline is that using it a lot makes it less of a big deal and makes them less likely to listen to softer methods. I've only been that rough with my akita when it was a very serious situation like her attempts to kill one of my cats as a puppy. Because I've rarely handled her rough if I so much as tap her with sharp voice or body language she flattens and immediately stops what she's doing. She's not scared of me, she knows I would never seriously hurt her, but she respects and she knows that I rarely use force so even the lightest amount of force gets her attention.
All puppies go through mouthy stages. You should encourage playing with toys only and not your skin but I don't entirely agree with the never letting a dogs mouth on you. Bite inhibition comes from testing the limits and knowing when a bite is too hard not just failing to bite. It's kind of like when someone disciplines their dog every time it growls. Eventually yes you get a dog that doesn't growl but you haven't changed the dog's dislike of the situation. The dog is still unhappy and now you don't get a warning of that before it bites. You just made an unpredictable animal instead of a safer one. I wrestled with my akita all the time while she was growing up and sometimes as an adult. She put teeth to skin all the time. She's never annoying about it, she stops the instant you tell her to, and she has wonderful bite inhibition. She can perfectly judge how much force to apply to leave a bruise, break the skin, or crunch bones together and carve teeth marks through flesh. She also has the knowledge of when each of those situations are appropriate. The last one has so far only been applied to a raccoon that was going to attack me. She didn't gain that knowledge by me never allowing her to test her teeth. She learned by me actually letting her put her mouth on me while we wrestled or played and then telling her when it was too rough. As well as leading by example in how rough I treated her, how rough I treated the other animals in the house, and how rough I let her treat the other animals in the house. Just be consistent about stopping play when it's too rough and only use as much force as is necessary. Many times as young puppies you do have to distract them with toys so they bite toys instead of skin.
Also work on being able to stop play. Start a game of tug of war with a toy, use a word for stop like "enough", and then stop pulling. Don't let go, just stop pulling, and go with the dog until it let's go of the toy. Then praise and begin play again. Then whenever things get out of hand all you have to do is say "enough" and the dog will stop whatever it's doing whether it's playing with you or something else. Generally when it's something else I also add "leave it". So if a cat or chicken is being roughed up or looks like it's going to get roughed up I can call out "enough! leave it!" and point the dogs the other way and they'll leave. Also work on things like "give" or "drop". Easiest with 2 toys. Have the dog play with or fetch one, tell it to "give/drop", and then pull out the 2nd toy and throw it. The dog will usually drop the first to go after the 2nd. Work up to holding the toy the dog has while pulling out the 2nd one and eventually to not switching toys. A very nonforceful way of getting dogs to give up even valuable items in the future. Little things like that will first off keep your puppy busy while learning so it doesn't have time to grab skin, second give you an arsenal of commands you can apply to stop behaviors, and third help move you up to leader of the pack instead of chew toy.
