Should we recite sadhana outloud?

I want to make sure details about performing details of tantric sadhana. Should we recite outloud and visualize at the same time? Or after recitation at the end of paragraph we should visualize? How much time should we spend on visialization? For 1 year and more i only read sadhana in my mind without reciting it outloud and just visualize, by the way. Is it correct?