Once she’s tinkled, you’re pretty safe for an hour or so. A good rule is every two hours even if she hasn’t eaten or had a sleep. Routine is your friend with a puppy :).
No matter how full the case is, its contents are simply fixed by straps and fasteners so that nothing can slip around inside. There is an extra bag, too. It is simply fastened into the add a bag holder which is integrated in the shell of the case and the trip can begin..