Long term travelers are forced to deal with a lot of challenges while on the road: dealing with bureaucracy, finding accommodations, navigating locales without knowledge of the language, and more. The difficulties begin even prior to traveling in figuring out what to bring on the road as a traveler's entire life can be fit in the contents of a 45-90 liter pack.
Going into the pros and cons of packing any item can be a headache, so it is almost easier to just pack the travel supplies you are comfortable with and go from there, regardless of what other people say.
Still, every item in your pack will have a shelf life, a period of time in which they can be reused over and over. This could be re-wearing of clothes, depleting a bottle of shampoo, or even the inevitability of electronics breaking. During the course of my travels I've been keeping track of my habits of product usage and come up with some good rule of thumb for many items that you might take with you.
