My friend IRL was shocked at the length of our bedtime 'routine' here, which has made me wonder what is average. Obviously it depends on lots of things, including age of children/how many children/special needs etc etc. But still curious.
I have two boys, DS1 is 2.5 years old, DS2 is 8 months old, and our routine takes roughly three to four hours. Sometimes less, but not often. They don't have special needs but DS2 is very spirited and takes a long time to wind down. I actually start the wind down process long before shower time, but it's not included in the 3-4 hours.
We have a shower together and then they go into their nappies & PJ's. We read a story or two and then sing a lullaby while I breastfeed DS2 to sleep. Then DS1 and I go and brush his teeth and then read several more stories, and then I lay down with him until he falls asleep (can take anywhere from 5 mins to an hour+!). Sometimes DS2 will wake up again and I settle him back down with a quick suckle.
Some nights I put DS2 down prior to DS1, but I prefer to do it all at the same time (showers etc), I just find it easier that way.