Rest times are determined by you in The Movement Athlete App. We are giving you a 'suggested rest time' and this is the time that will be used in calculating total workout time. But you always have the option to rest more or as long as is needed to do the next set, with the disclaimer that long rests will add to total workout time.
Why? Rest can be very individual. Some people are good to go on basically any exercise after 30s. Other people need 3 mins. Age, training experience, other activities, work, time of day, so many things can affect it and at this stage it would be impossible for the app to account for all factors. But in the future we are looking into improving and implementing those algorithms.