I am planning on doing mantra sadhana during this Navratri for Durga Worship. I intend to do 108 repetitions (per day) of a certain stotram. I will take Sankalpa for the same before starting my sadhana on the first day.
But I want to break down the mantra japa into two sessions (54 japas each) - One in the morning and the other in the evening. This is because doing 108 repetitions in the morning will take too long and I have other obligations (College, etc.). Is this permissible according to the Shastras? Or, is it mandatory to complete the 108 repetitions in one-sitting?