Quickbase tasks are based on a five-day work week. For example, if Task 1 will take 2.5 days to complete and it begins on a Thursday, it will end on the next Monday at midday, and its successor task will start at that time. But say you run a 24/7 kind of shop. Your business is open on weekends, and you don't want Quickbase to skip them.
You can change the work week to include weekends if you want. In a project management application that uses dependencies, open the Field Properties page for the end date field and turn off the Work week is Monday - Friday checkbox.