I'm the opposite to Louise. My 2 don't need the dummy for naps at all during the day, nor during the night. They go to sleep brilliantly on their own.
However, just before going down for the night, they have to have the dummy, Sam manages to keep it in no problem, but Lydia needs a bit of help. She tends to spit it out, but then decides she wants it, so back in it goes...this goes on for about an hour until she drops off.