Here is a link:
http://www.babycenter.com/0_how-much-sleep-does-your-chil...
She sounds perfectly fine. I have 2 kids, and
you are lucky she is regular, and has a pattern already. And keep in mind, she IS sleeping consistently, already.
Go by HER cues.
Your baby is normal.... and she IS sleeping REALLY REALLY good at night. Her waking every 4-5 hours is nothing and she IS sleeping through the night.
Remember, babies do not sleep "all night" as in the adult connotation of it. A baby is considered sleeping through the night if they are sleeping at least 5-6 hours straight. Your baby IS doing that.
If a baby is tired, they will fall asleep. If naps/sleep is denied...then they get fussy and even more "hyper" because they are over-tired. If a baby sleeps/naps on their own.. then good.
EVENTUALLY, if you want to cut out 1 nap... then it should be done IN TIME. Not in 1 day. But also go by her cues... and even if you cut out one nap, there will be days when she WILL need an extra nap. So do so.
Right now, it seems she is still doing real well with her nap and sleep schedule. So, I would not mess it up too much or change it (suddenly) or she will have "real" sleep issues.
Your baby, does not have sleep problems. She is a GREAT sleeper and napper. You are very lucky!
I would let her be. Don't fix it if it ain't broken. She knows herself and sleeps well already.
My son, was like that too... REAL regular about naps and sleep. And at that same age, he was napping 3 times a day too. Then from about 1-2 years old, he napped twice a day. Then at 3 years old he still naps 1 time a day. That is what HE needed and I went by HIS cues. That is just how my son was. And I was so glad, because he sleeps and naps so well. BUT, yes, as with ALL babies/toddlers... he still woke during the night and especially during growth-spurts/developmental changes/when he hit milestones/teething etc. Which is normal. But, he was and still is a great sleeper. It was when he was about 2 years old, that he slept ALL night (as an adult would), and that is the normal natural continuum and tendency for kids.
Oh adding this: at 9 months, it was a growth-spurt age. So, she may just need extra feedings/nursings. She is growing, her intake needs are naturally increasing. Through the 1st year of life, per our Pediatrician, a baby needs still to be fed on demand.... since their growth is so rapid and they are hitting growth-spurts and developmental changes and brain wise too, and perhaps teething. And these things often are happening all at the SAME time... not just one at a time. So it tweaks the baby too. Normal though.
Sleep is not static with a baby. There will be phases... but I think your baby is very regular and sleeps well.
All the best,
Susan