In other words, you’ll get more writing done each week and better writing done if you write for 30 minutes every day then 3 hours only once a week.
How long can you realistically write each day? 30 minutes? An hour? 2 hours? More? To be honest, I don’t think the length of time matters as much as the consistency. Staying in your story or project day in and day out will help you keep track of it and maintain momentum. In other words, you’ll get more writing done each week and better writing done if you write for 30 minutes every day then 3 hours only once a week.