They can also adapt just fine to a very variable daily structure.
I have a chronic illness that makes it very difficult to maintain much of a routine, especially a morning routine. My dogs are as forgiving if I wake at 10:00 am as they are if I wake earlier. They don't pester me to get up and if I wake up early just long enough for a quick trip to the bathroom (for me, not for them) they usually just watch to see if I'm actually getting up or if I'm going back to bed for a while. They will start to stir around 10:00 if I haven't gotten up yet, but they're not insistent about.
The rest of my days are just as unpredictable. Sometimes we go out and do something, others nothing will happen at all. They're fine with it. They do know from watching me if I'm getting ready to go out, usually before I've actually begun getting ready, and whether or not they'll be able to go along. But since that's not consistent on a day to day basis it's nothing anyone could call a routine.
They only time they get antsy about anything being done "on time" is feeding, but even then they'll just go and lie down to wait if I (rarely) tell them I'm not ready yet.
I think the whole dogs-need-a-routine thing is vastly overrated, a holdout from the often silly Barbara Woodhouse approach to training dogs, which I thought was nonsense then. Some people do better with routines and perhaps they project this onto their dogs. I don't know. But for the past 20 years since I was forced to stop working, all of my dogs, including fosters and most of whom are now long gone, have thrived with my inconsistent lifestyle.
That's not to say that they aren't the most incredible time keepers, though. They are, as well as pretty darned amazing GPS systems as well. They might not be able to tell me how to get somewhere, but they sure know where we're going if they've ever been there a couple of times before.