If I think there's even a remote chance that I might need to return an item, I'll keep the product packaging for a couple of months as well, no matter how big or small the purchase. It's easy enough to do if you have the room.
I went through an old stack of receipts a couple months ago. I had receipts for tools, clothing and CDs that I purchased in the late 80s.
Me too. When I moved last year, I even found a couple of appliance boxes up in the very top of a very large closet for things that had bitten the dust years before.
Hell, back before they changed their policy to 90 days, I once returned a circular saw literally a year after I bought it (but ended up never using.) Since I had the receipt, they took it back (after sending for a guy from the tool department to scrutinize it
very carefully to make sure it hadn't been used), but without it I'd have been SOL since apparently the SKU was long gone from their POS system... (I actually felt a little guilty about that particular return but hey, money's money and I didn't write their policy for them after all.)
But even still, I have occasionally returned things without a receipt, usually because I forgot it at home, and Home Depot is very forgiving about that sort of thing. The only time it's a problem is if the item has been discounted since you bought it, in which case they'll only give you the lowest price it's sold for during some period-I-don't-recall prior to the return....