Unfortunately, this is a question that is really difficult to give a clear answer.
There are at the present point, several published studies regarding duration time of standing, who argue that the rime may vary from 12 minutes per day until 2 hours, 5 days per week.
In any case the frequency more represented is between 30 and 60 minutes per day.
Clinical experts such as Rosen (2010) suggest a use from 45 minutes to 2 hours daily, while Paleg according to Silberstein (2008) recommended from 7 to 10 hours per week if the aim is to increase bone density.
It also appears that the use of standing device depends on the age of the individual, the diagnosis, the tolerability of using the frame in an upright posture, the type of benefits that you are looking for.
It has recently been reported by specialists that using the standing frame more and more times during the day and for short periods can give more benefits of a single extended period, as evidenced by Wechsler and Silberstein through their studies from 2008 to 2011.