Dogs, especially working dogs like dobermans and shepherds, get bored. If you’re “too busy” for the dog, you shouldn’t own it, simple as that. I’ve got a shepherd, and he’s a lot of work, but I make the time for him because I knew he would be a lot of work before I got him. The smarter the dog the more you have to exercise their brains to keep them out of trouble.
The kong is a good suggestion. I fill mine with peanut butter then throw it in the freezer overnight. It takes the dog a while to get the peanut butter out that way. I used to jam little dog biscuits in there but it only took him about 20 minutes to figure out that tossing the kong in the air and letting it bounce would get them out almost immediately. Smart little bastard. It was fun to watch until he bounced it off my hdtv. That was when I switched to frozen peanut butter.
I just ordered a book on search and rescue training and I’m going to start working with him on that next. As long as you’re training them they keep out of trouble.