How does one determine how many of one thing to keep? For example, how many pens do you keep? Do you have a limit on the number you bring into your home? Since pens don't take up a lot of space, they're probably not high on your list of items to downsize.
When I'm working with a client on an office organization project, I like to take time to make sure all of the pens still contain ink and also find out which are my client's favorite pens to use. It's also a good time to assess the number of pens contained in the office supply drawer. As a general rule, I like to cut the amount of items in half. If a client has 70 pens, we'll talk about downsizing to 35.
Although the rule of half can sometimes be unrealistic, most times it can be an effective way to keep your items in check (i.e. duplicates of items). The next time you're organizing a drawer, keep the rule of half in mind as you consider how many of each to keep.