Niles doesn't need the leash to reassure him as much as Frasier does. He is, however, more insecure without his brother and so I keel a slip leash with me when I walk him solo, just in case.
These boys are gigantic and so it is so easy to forget they are just babies still. Their training needs clean up, which is what I will be working on until they go home, then they just need it to be their way of life as much as possible. Not allowing them to "run and hide" when asked to do something they don't want to do is critical because if that behavior is allowed to pass then it will continue into their adulthood and it will definitely be annoying at a crucial point. High expectations will be the best things these puppies can receive from their owners.
Luckily motivating them with praise is always easy as they can never get enough of being touched. Sweet babies indeed.