Are all your To Do lists in one room?
If they are in one room, are they all in one location in that room?
In that location, are they on one piece of paper, one file or in one file folder?
Are the similar or related items identified as relating to each other?
Are similar actions listed together?
Are they sorted by date identified, date due, level of importance, level of urgency, relevance to your objectives?
Do you know when the items have been accomplished?