I thought the same thing about the OP.No, not really. It's pretty easy to do. I have a lot of fun doing it.
The OP was unconcerned about the exercise requirements. He said that he was fine doing two long walks a day (plenty for a Great Dane) and has done his research on the breed. I have no reason to assume he's not responsible.
You can't tell a good dog owner by solely (or even mostly) how long they can spend home with their dog. For a little anecdote, I know two bc owners. One has a yard and stays at home the other has no yard and works and goes to school. But the lady that stays at home with the yard keeps her dog outside and really does little with it even though she could. That dog is a mess. The girl that has the bc in an apartment and it's home alone 8-9 hours a day has a very well adjusted dog because she knows what that kind of dog needs and makes sure to spend her free time giving him what he needs.