My trips work very well with a carry-on, but there are times when it can make sense to check a bag and I don't consider it to be a "rookie mistake", necessarily. I also think it is more difficult for women -- not ALL women, but many. Most of my travel is leisure; three nights is typical and five nights is about max. There are also times when I will check a piece of luggage on the return, if there has been some shopping involved.