At a minimum, a shift is two hours long (or two consecutive one-hour shifts). Each hour is selected separately in the Instacart delivery app. With blocks of three or four shifts, shoppers get a 20-minute break.
In-store shoppers (ISS) work scheduled shifts with hours set by the employer based on store needs and shopper availability. Shifts are not longer than 8 hours. On Instacart forums, workers state employees must be available for at least 16 hours per week, with 8 of those hours falling on Saturday, Sunday, or Monday.