They break up the day.
A full day with babies and toddlers can feel like an endless stretch of monotonous routine to figure out how to entertain them. Days can drag on as parents furiously rack their brains on what to do next. Oftentimes, this can lead to parents giving up and turning popping a kid in front of a TV into longer than they'd like.
However, with time-ins, Dr. Karp calls them "bite-size bits." They break up the day to satisfy a child's appetite for Mommy and Daddy. I like to write down our schedule for the next day the night before, and when I do, I schedule in those time-ins. The schedule can be adjusted as our day proceeds. For example, if I am in the middle of working on something, and I notice my son is getting fussy, I'll take a quick break for a 10-minute time-in to whet his whistle. He is usually satisfied with that, and I can return to my work. It also teaches him patience. Mommy and Daddy cannot be by his side 24/7, so we'll say, "When you hear Mr. Dinger, Mommy will come play with you. Wait, wait, wait." He seems to understand and can entertain himself a little longer. I get to finish wiping down the counters. Win/Win.