This advice seems catered for consultants or others who take 1-2 day trips with a fairly high frequency. That being said, I think overpacking is definitely the biggest issue with. Nwbie travellers: I remember bringing a rollerbag for an overnight trip, in addition to a stuffed backpack, and all it led to was me having a clean set of clothes and unworn shoes when I got home, and getting stuck in the T's revolving exit door.