Yeah, age is a huge factor. Puppies need routine to keep the house training going, but adults can be more flexible. My doggies go out after a maximum of 10 hours. If I have an early class and have to leave at 7:30, they go out before. But if I have a later class or on weekends, they'll sleep in with me, but I'll bring them out later the night before. They really don't care as long as they don't have to wait too long.
Oh- you might not get a dump on the irregular walks though. Like if your dog dumps at 10AM usually, and you walk her at 8AM, chances are she's not ready for a dump.