It sort of depends when I got hired my training was a 20 hour week, but for the week you are training you go according to the schedule of your trainer not your own. I wouldn't be too worried about it until you get properly scheduled after training, but then again it's different per Starbucks. Four to five hour shifts are common in my experience though since Starbucks doesn't like setting aside lunch hours for partners, just usually it is more then two days of four hour shifts.