I just looked through the code that's creating new preset lists. It looks at the number of the existing preset lists and creates the new preset list with a number that is one greater than the highest list number it encountered. So, it shouldn't give a new list a number of 7 unless it found a list already with the number 6. It will skip over numbers though. So, if there are lists numbered 1, 2, and 6, a new list will be given the number 7 and not the number 3.