Currently can only set minimum time setting overall, however i have found this to be a detriment if you offer free voices, with or without a sub only setting. To prevent a free voice from being set to go on for a long time i have to set the min time low, however this negatively impacts those voices that require bits as it means to get a decent time for their bits value they have to spend much higher amounts. Eg min time 5s and lowest price of 50 bits means 500 bits for 50s voice change, isn't really value, but 50s is plenty for free as I restrict to sub only and after so often the sub would get more value out of the sub cost.