I think it varies hugely depending on routine and ages. Older kids pretty much sort themselves out, some kids don't have a bath every night, some shower in the morning so rarely have baths at bedtime.
I have a 2yo and a 5yo and 40 minutes is about right for bath, teeth, pyjamas, stories, bed. Usually put the 2yo to bed after stories then the 5yo reads to us so that takes an extra 10-20 minutes, and twice a week is hair wash night for her (she has long, thick hair) so that adds on another 10 minutes to dry it.
They take anything between 10 mins to 1 hour to actually go to sleep though but I wouldn't count that time as it has no input from me. They play with their teddies and sing/talk to themselves until they fall asleep.