Our dysfunctional system:
Any item not specifically addressed to us goes straight in the recycling (adverts etc).
An item addressed to us that doesn't need to be actioned (e.g. bank statement) goes into a "to be shredded and binned" pile. This pile gets sorted about once a year. In the meantime I find that leaving boring-looking letters unopened in their envelopes works best here as it creates less mess in this pile.
An item that definitely should be actioned soon, goes into a "to be actioned" pile, until the action is no longer valid, relevant or required. The item can then safely be disposed of.
If an item is really important and immediate (like a form for school) it can't go into the "to be actioned" pile for obvious reasons, and instead it tends to hang perilously around the kitchen table or sofa, until actioned.
Annual stuff like insurance, utilities, usually can be found on email, failing that I assume the supplier will have records of everything, so these can go into the pile to be shredded and binned. Sometimes they go into the "to be actioned" pile if we really should look at the item to change providers or something, at some point, soon.
Long-term stuff like marriage certificates, house deeds etc are filed away very nicely indeed with labels and such-like.
Despite all these rules, many bits of paper just cannot be classified into any of the above categories. Sadly the system cannot cope with these exceptions and so they are placed on the nearest surface and eventually tidied into various miscellaneous piles around the house.
Examples of these exceptions around me now are: a Kinder egg instructions sheet which DS would dearly miss (especially as the toy has been lost); a return-slip for an online purchase which DH has yet to try on; a half-written thank you card which is pending someone confirming what exactly the gift was and if it was shared from two people or just from one of them.