Some people can immediately toss mail, catalogs, flyers, and other items they know they don't want or won't use. They don't need to stack them up and then go through them at a later time to determine then that they don't need them. They can make a decision now to keep some order in what they retain. They are able to do the same thing with old or outdated clothes and fashions, expired foodstuffs, old toys, or broken items (or ones with missing parts).
Some people tend to hang onto most everything - at least temporarily. They know they likely won't want or need all of it, but it's easier to hang onto it in the short-term than to make the decision to get rid of it. Sometimes that temporary status gets erased and those items become long-term members of the family. Meanwhile, even if many of those items eventually are discarded, they add to the amount of accumulating clutter in the home while they are present.
Then, there are people who seem to hang onto everything - just in case. There is the feeling that one never knows when they might need something that was left over from assembling a toy or piece of furniture. When a small appliance breaks or stops working - or it's replaced by a newer version - that item is kept for parts, power cords, or the possibility that it can be returned to running order at some future date. Typically, that never happens, and the parts from older models never seem to fit the newer ones anyway.
Regardless of how much or how little a person hangs onto, many people recognize that they need some order in their lives and in their homes. Springtime is a convenient and customary time for this to occur. A fairly common practice, therefore, is creating folders or envelopes for paper storage, with boxes, bins, and plastic containers for larger or bulkier items.