In general at my Starbucks, unless we're working with another person, we just don't take breaks. There's a semi-decent number of people in our store who are trained for it, but we're usually made to feel extremely guilty if we have to go bother them to watch the place. I always make sure to take my meal before the person in front of me leaves (they're usually very early in my shift), and have only ever had to shut down twice during the past month when after being slammed for hours I had no more syrups made, and nobody else to make them while I helped customers.
I've heard references to Starbucks TMs with attendance issues in the past, but the group we have now is really solid, and especially the teenagers and college-age kids (including me) are really likely to come in if somebody has called out (not an affront to our older coworkers, but we just don't have kids or other jobs).
Our Food Avenue, though, has a lot of attendance issues, and the work-ethic among their TMs is much lower. The TL seems at her wit's end, and I've already talked to her about getting trained over there too. It's kinda depressing how much stress her employees give her, and she's so nice still.