With Buzz (now 7), I was instructed to wake him 2 hours after completion of the last feed, only at night time. This was because with Belle, I was unable to breastfeed (long story) and she had lost a dangerous amount of weight. Since I was also nursing Buzz, the doctor had recommended the waking thing to be sure he was getting enough. After a few weeks, we were all confident enough to let him sleep. With #3, we let her dictate her own schedule.
Bottom line, every family is different, you have to do what makes Mom and Baby both feel good. They may have a sound basis for this, or may look back at it and laugh--but if it gets them through for now, hey, I'm happy for them.