No, DD1 was never really exclusively BF. She never knew what to do.
We mucked about mixed feeding until she was 4.5/5 months old, then one day she just decided to just scream and throw a massive tantrum every time I tried, so we gave up.
DD2 obviously knew what she was doing from the first time I held her to my breast, just after she was born. Second time I tried, she just fed.
As she got older she still seemed to know instinctively what to do. She worked out how to position her self to breath as she lost her babies snub nose, she learnt very quickly not to bite (except as she feel asleep, which need a quick unlatch when you felt her relax, for a bit).
She seemed to instively understand that mum would continue feeding you if you went back to your own bed easily in the night and replaced night feeds with a drink of very week squash from a cup by your bed.
She instinctively never asked in public when she was older.
I just wish she was as thoughtful and reasonable about everything else in life 
Also non of this would have happened if DD1 hadn't been total understanding and not in the least jealous of her sister.
She liked me feeding her when she was small because I read to her and paid attention to her Duplo creations. She got Daddy to read to her at night and he's much better at bed time stories than me.
DD1 is 3years older which meant she was at preschool 3-4 mornings a week and also old enough to understand babies were different.
I'm incredibly lucky, the DDs are total opposites in a 1000 ways, they ought fight, but they don't!
DD2(13) was telling me last night how much she loves her big sister despite her being quirky and a bit of an embarrassment. (Totally fair assessment, DD1 is dyslexic and her social skills are a bit like her spelling).
Good luck and here's to an peaceful evening off, had DD2 not let DH put her to bed by 7/8 months I wouldn't have been impressed. You are totally right there comes a point when mum needs some time off.