Where I work, the pharmacy prepares all IVs and drips, always. But we mix up many of our own meds, especially antibiotics. For these, we made a book for each bedside that lists all the antibiotics we use. There are instructions on standard dilutions (mixing to a final concentration acceptable by the neofax or peds dosing manual), compatibilities, running times, etc. So when we double check our meds with someone, we tell them how we diluted it and 99% of the time it's in our book so everyone is on the same page, and the resulting med is dilute enough for a neonate. It kills me that we draw them up sometimes, though, because we have to toss out the vials afterwards and we waste SO MUCH medication that way!!! We'll take like 50mg out of a 1gm vial and that's it. If it were made in pharmacy under the hood and then refridgerated, many of them would last a week down there and they could just draw us up each dose. But nooooo, we apparently like to waste all those expensive antibiotics...and then hear all about shortages. Wonder why!
As for drips, I can imagine that in an emergency we'd have to draw them up, but this is only when we're on transport. We use that rule of 6's, which I hate. But basically, if you want single concentrated dop/dob, all you do is 60mg times the baby's weight, add that to a 100cc bag of 0.9NS or D5W, and then 1cc=10mcg/kg/min. If you want double concentrated it's 120mg times the weight. (We don't do triple or quadrouple, personally.) Insulin, I have no idea how to mix, was never taught.
I do agree, that for drips and IV bags, it's safest for pharmacy to do it.