I actually have a tendency to underpack, even with my lists. For this trip, I have two weeks in London before I head for the podcast cruise. I thought I was doing well, I had a day by day list of what to wear while on the cruise and in WDW, then I made a list of 9 work day outfits, and totally forgot about the weekend in London.
Good thing they have a washer and dryer here. I do however, always overpack undies, @ least one extra.
So far I haven't found that I've forgotten anything.