My 18-month-old usually naps 2-3 hours a day, but never at any real predictable time. We have a late-to-bed, late-to-rise lifestyle right now and she's a natural night owl. DH works nights, usually from 2-10PM or 3-11PM, and Ela likes to be up when he gets home. We wait for him to get home to have a late dinner together, so that forces our nights to be later.
She usually falls asleep for the night around 1AM (though last night she decided sleep was for suckers and tried to keep playing in bed til almost 3AM! wtf) She generally sleeps 10 hours a night, down from 12 a few months ago. The best-case scenario is when she takes her nap around 5PM and sleeps til 7PM. But sometimes she fakes me out, acting like she's sleepy but fighting it til 8 or 9. Those are usually the nights when she stays up well past midnight.
I'm starting a part-time job at the end of August, and I'll have to start getting up around 8AM. It should be interesting to see what this does to our schedule. I wouldn't mind it if we all started getting up and going to bed a bit earlier than we currently do, but I'm not sure how that will pan out with DH's schedule.