Puffin of my 3 kids only one came remotely close to meeting the sleep begets more slep adage. She was the only one that napped much beyond 48 months too. 9:30 would be too late for my kids but that's because they all wake at the crack of dawn regardless of bedtime. If they could sleep longer in the mornings then bedtime would only depend on getting enough hours in and the practical requirements of our morning routine...
Well to be fair one of mine wakes at 6 when he goes to bed at 7 - but if I put him to bed at 8 he wakes up at 5 and so on. The tireder he is allowed to get the worse he sleeps and the earlier he wakes and the more he cries and can't manage other kids and their games. The other would actually prefer a 9 pm bed time and to sleep late but it works better to put him to bed at 7 and let him read while he settles as he is a slow to settle person. If you let him stay up he takes longer to settle.
My older did nap occasionall past 4 but that is unusual her - and he still went to he'd early (he is pretty high energy) but the younger stopped at about 2. He was one of those babies who appear not to need sleep but are actually happier if you insist on it.
The only reason I queried it is it sounded like her parents both work which usually means sleeping late is not an option.
