This is true! My sister was rocking her kids to sleep when they were 4 and 5 years old. It took 45 min+ each night. My SIL co-sleeps with her 9yo and 2yo daughters because that's how she's always done it. ...And 50% of her FB posts are about how tired and sleep-deprived she is. I don't claim to be a baby-sleeping expert, but
I think it's best not to start a habit or sleep routine that you don't want to continue for years.